diff --git a/animals.lisp b/animals.lisp
index 09ac297..3f5634c 100644
--- a/animals.lisp
+++ b/animals.lisp
@@ -8,58 +8,28 @@
 ;;;; (c) 2018 Daniel Vedder, MIT license
 ;;;;
 
+;;TODO Change to African species
+;;XXX bird species?
 
-(defvar *animals* NIL)
-
-(let ((species-list NIL))
-	(defun register-species (symbol-name species-object)
-		(setf species-list
-			(cons (list symbol-name species-object) species-list)))
-
-	(defun get-species (symbol-name)
-		(cassoc symbol-name species-list)))
-
-(defmacro new-species (name &body body)
-	`(register-species ,name
-		 (make-instance 'species ,@body)))
-
-(let ((max-id 0))
-	(defun add-animal (species position)
-		"Create a new animal of the given species"
-		(let ((a (make-animal :id max-id
-					 :pos position :species species
-					 :health (.max-health species))))
-			(incf max-id)
-			(setf *animals* (append *animals* a)))))
-
-;;; SPECIES DEFINITIONS
-
-;;XXX Change to African species?
-;;TODO bird species
-
-(new-species 'deer
-	:name "deer"
+(new-species deer
 	:strength 3 :max-health 10 :aggression 0
 	:group-size 10
 	:habitat '(forest grassland)
 	:drops NIL) ;TODO
 
-(new-species 'boar
-	:name "boar"
+(new-species boar
 	:strength 7 :max-health 15 :aggression 5
 	:group-size 5
 	:habitat '(forest)
 	:drops NIL) ;TODO
 
-(new-species 'wolf
-	:name "wolf"
+(new-species wolf
 	:strength 10 :max-health 20 :aggression 20
 	:group-size 6
 	:habitat '(grassland)
 	:drops NIL) ;TODO
 
-(new-species 'bear
-	:name "bear"
+(new-species bear
 	:strength 20 :max-health 30 :aggression 20
 	:group-size 1
 	:habitat '(forest)

diff --git a/animals.lisp b/animals.lisp
index 09ac297..3f5634c 100644
--- a/animals.lisp
+++ b/animals.lisp
@@ -8,58 +8,28 @@
 ;;;; (c) 2018 Daniel Vedder, MIT license
 ;;;;
 
+;;TODO Change to African species
+;;XXX bird species?
 
-(defvar *animals* NIL)
-
-(let ((species-list NIL))
-	(defun register-species (symbol-name species-object)
-		(setf species-list
-			(cons (list symbol-name species-object) species-list)))
-
-	(defun get-species (symbol-name)
-		(cassoc symbol-name species-list)))
-
-(defmacro new-species (name &body body)
-	`(register-species ,name
-		 (make-instance 'species ,@body)))
-
-(let ((max-id 0))
-	(defun add-animal (species position)
-		"Create a new animal of the given species"
-		(let ((a (make-animal :id max-id
-					 :pos position :species species
-					 :health (.max-health species))))
-			(incf max-id)
-			(setf *animals* (append *animals* a)))))
-
-;;; SPECIES DEFINITIONS
-
-;;XXX Change to African species?
-;;TODO bird species
-
-(new-species 'deer
-	:name "deer"
+(new-species deer
 	:strength 3 :max-health 10 :aggression 0
 	:group-size 10
 	:habitat '(forest grassland)
 	:drops NIL) ;TODO
 
-(new-species 'boar
-	:name "boar"
+(new-species boar
 	:strength 7 :max-health 15 :aggression 5
 	:group-size 5
 	:habitat '(forest)
 	:drops NIL) ;TODO
 
-(new-species 'wolf
-	:name "wolf"
+(new-species wolf
 	:strength 10 :max-health 20 :aggression 20
 	:group-size 6
 	:habitat '(grassland)
 	:drops NIL) ;TODO
 
-(new-species 'bear
-	:name "bear"
+(new-species bear
 	:strength 20 :max-health 30 :aggression 20
 	:group-size 1
 	:habitat '(forest)
diff --git a/biomes.lisp b/biomes.lisp
index a723d8d..88d76c0 100644
--- a/biomes.lisp
+++ b/biomes.lisp
@@ -3,39 +3,11 @@
 ;;;; set in Africa.
 ;;;;
 ;;;; Biomes are habitat types, that provide default functions for patches.
-;;;; This file defines the biome struct and the inbuilt biomes.
+;;;; This file holds the biome definitions.
 ;;;; 
 ;;;; (c) 2018 Daniel Vedder, MIT license
 ;;;;
 
-;; Biome struct and register
-
-(defstruct biome
-	(name "")
-	(ground "")
-	(features '()) ;an alist of possible features and their 1/p probabilities
-	(char #\.) ;default map display character
-	(col ':white)) ;default map display colour
-
-(let ((biome-list NIL))
-	(defun register-biome (symbol-name biome-object)
-		(setf biome-list (cons (list symbol-name biome-object) biome-list)))
-
-	(defun available-biomes ()
-		(keys biome-list))
-
-	(defun get-biome (symbol-name)
-		(cassoc symbol-name biome-list)))
-
-(defmacro new-biome (name &body body)
-	`(register-biome ',name
-		 (make-biome
-			 :name ,(symbol-to-string name)
-			 ,@body)))
-
-
-;; Biome definitions
-
 (new-biome grassland
 	:ground "tall elephant grass"
 	:char #\; :col ':yellow

diff --git a/animals.lisp b/animals.lisp
index 09ac297..3f5634c 100644
--- a/animals.lisp
+++ b/animals.lisp
@@ -8,58 +8,28 @@
 ;;;; (c) 2018 Daniel Vedder, MIT license
 ;;;;
 
+;;TODO Change to African species
+;;XXX bird species?
 
-(defvar *animals* NIL)
-
-(let ((species-list NIL))
-	(defun register-species (symbol-name species-object)
-		(setf species-list
-			(cons (list symbol-name species-object) species-list)))
-
-	(defun get-species (symbol-name)
-		(cassoc symbol-name species-list)))
-
-(defmacro new-species (name &body body)
-	`(register-species ,name
-		 (make-instance 'species ,@body)))
-
-(let ((max-id 0))
-	(defun add-animal (species position)
-		"Create a new animal of the given species"
-		(let ((a (make-animal :id max-id
-					 :pos position :species species
-					 :health (.max-health species))))
-			(incf max-id)
-			(setf *animals* (append *animals* a)))))
-
-;;; SPECIES DEFINITIONS
-
-;;XXX Change to African species?
-;;TODO bird species
-
-(new-species 'deer
-	:name "deer"
+(new-species deer
 	:strength 3 :max-health 10 :aggression 0
 	:group-size 10
 	:habitat '(forest grassland)
 	:drops NIL) ;TODO
 
-(new-species 'boar
-	:name "boar"
+(new-species boar
 	:strength 7 :max-health 15 :aggression 5
 	:group-size 5
 	:habitat '(forest)
 	:drops NIL) ;TODO
 
-(new-species 'wolf
-	:name "wolf"
+(new-species wolf
 	:strength 10 :max-health 20 :aggression 20
 	:group-size 6
 	:habitat '(grassland)
 	:drops NIL) ;TODO
 
-(new-species 'bear
-	:name "bear"
+(new-species bear
 	:strength 20 :max-health 30 :aggression 20
 	:group-size 1
 	:habitat '(forest)
diff --git a/biomes.lisp b/biomes.lisp
index a723d8d..88d76c0 100644
--- a/biomes.lisp
+++ b/biomes.lisp
@@ -3,39 +3,11 @@
 ;;;; set in Africa.
 ;;;;
 ;;;; Biomes are habitat types, that provide default functions for patches.
-;;;; This file defines the biome struct and the inbuilt biomes.
+;;;; This file holds the biome definitions.
 ;;;; 
 ;;;; (c) 2018 Daniel Vedder, MIT license
 ;;;;
 
-;; Biome struct and register
-
-(defstruct biome
-	(name "")
-	(ground "")
-	(features '()) ;an alist of possible features and their 1/p probabilities
-	(char #\.) ;default map display character
-	(col ':white)) ;default map display colour
-
-(let ((biome-list NIL))
-	(defun register-biome (symbol-name biome-object)
-		(setf biome-list (cons (list symbol-name biome-object) biome-list)))
-
-	(defun available-biomes ()
-		(keys biome-list))
-
-	(defun get-biome (symbol-name)
-		(cassoc symbol-name biome-list)))
-
-(defmacro new-biome (name &body body)
-	`(register-biome ',name
-		 (make-biome
-			 :name ,(symbol-to-string name)
-			 ,@body)))
-
-
-;; Biome definitions
-
 (new-biome grassland
 	:ground "tall elephant grass"
 	:char #\; :col ':yellow
diff --git a/classes.lisp b/classes.lisp
index d559409..d30eb90 100644
--- a/classes.lisp
+++ b/classes.lisp
@@ -7,6 +7,7 @@
 ;;;; (c) 2018 Daniel Vedder, MIT license
 ;;;;
 
+
 (defclass item ()
 	;; The base class of all game items.
 	((name :accessor .name :initarg :name :initform "")

diff --git a/animals.lisp b/animals.lisp
index 09ac297..3f5634c 100644
--- a/animals.lisp
+++ b/animals.lisp
@@ -8,58 +8,28 @@
 ;;;; (c) 2018 Daniel Vedder, MIT license
 ;;;;
 
+;;TODO Change to African species
+;;XXX bird species?
 
-(defvar *animals* NIL)
-
-(let ((species-list NIL))
-	(defun register-species (symbol-name species-object)
-		(setf species-list
-			(cons (list symbol-name species-object) species-list)))
-
-	(defun get-species (symbol-name)
-		(cassoc symbol-name species-list)))
-
-(defmacro new-species (name &body body)
-	`(register-species ,name
-		 (make-instance 'species ,@body)))
-
-(let ((max-id 0))
-	(defun add-animal (species position)
-		"Create a new animal of the given species"
-		(let ((a (make-animal :id max-id
-					 :pos position :species species
-					 :health (.max-health species))))
-			(incf max-id)
-			(setf *animals* (append *animals* a)))))
-
-;;; SPECIES DEFINITIONS
-
-;;XXX Change to African species?
-;;TODO bird species
-
-(new-species 'deer
-	:name "deer"
+(new-species deer
 	:strength 3 :max-health 10 :aggression 0
 	:group-size 10
 	:habitat '(forest grassland)
 	:drops NIL) ;TODO
 
-(new-species 'boar
-	:name "boar"
+(new-species boar
 	:strength 7 :max-health 15 :aggression 5
 	:group-size 5
 	:habitat '(forest)
 	:drops NIL) ;TODO
 
-(new-species 'wolf
-	:name "wolf"
+(new-species wolf
 	:strength 10 :max-health 20 :aggression 20
 	:group-size 6
 	:habitat '(grassland)
 	:drops NIL) ;TODO
 
-(new-species 'bear
-	:name "bear"
+(new-species bear
 	:strength 20 :max-health 30 :aggression 20
 	:group-size 1
 	:habitat '(forest)
diff --git a/biomes.lisp b/biomes.lisp
index a723d8d..88d76c0 100644
--- a/biomes.lisp
+++ b/biomes.lisp
@@ -3,39 +3,11 @@
 ;;;; set in Africa.
 ;;;;
 ;;;; Biomes are habitat types, that provide default functions for patches.
-;;;; This file defines the biome struct and the inbuilt biomes.
+;;;; This file holds the biome definitions.
 ;;;; 
 ;;;; (c) 2018 Daniel Vedder, MIT license
 ;;;;
 
-;; Biome struct and register
-
-(defstruct biome
-	(name "")
-	(ground "")
-	(features '()) ;an alist of possible features and their 1/p probabilities
-	(char #\.) ;default map display character
-	(col ':white)) ;default map display colour
-
-(let ((biome-list NIL))
-	(defun register-biome (symbol-name biome-object)
-		(setf biome-list (cons (list symbol-name biome-object) biome-list)))
-
-	(defun available-biomes ()
-		(keys biome-list))
-
-	(defun get-biome (symbol-name)
-		(cassoc symbol-name biome-list)))
-
-(defmacro new-biome (name &body body)
-	`(register-biome ',name
-		 (make-biome
-			 :name ,(symbol-to-string name)
-			 ,@body)))
-
-
-;; Biome definitions
-
 (new-biome grassland
 	:ground "tall elephant grass"
 	:char #\; :col ':yellow
diff --git a/classes.lisp b/classes.lisp
index d559409..d30eb90 100644
--- a/classes.lisp
+++ b/classes.lisp
@@ -7,6 +7,7 @@
 ;;;; (c) 2018 Daniel Vedder, MIT license
 ;;;;
 
+
 (defclass item ()
 	;; The base class of all game items.
 	((name :accessor .name :initarg :name :initform "")
diff --git a/data.lisp b/data.lisp
new file mode 100644
index 0000000..23d9e39
--- /dev/null
+++ b/data.lisp
@@ -0,0 +1,107 @@
+;;;;
+;;;; Naledi ya Africa ("Star of Africa") is a rogue-like survival game
+;;;; set in Africa.
+;;;;
+;;;; This file stores all game data.
+;;;;
+;;;; (c) 2018 Daniel Vedder, MIT license
+;;;;
+
+;;; PATCHES
+
+(let ((world NIL))
+	(defun set-world (w) (setf world w))
+
+	(defun world-size () (length world))
+
+	(defun save-topography (file-name) ;XXX (re)move this?
+		"Save the world topography as a text file"
+		(debugging "~&Saving world to file ~A" file-name) ;debug
+		(with-open-file (tf file-name :direction :output)
+			(dolist (row world)
+				(format stream "~&~A~%"
+					(string-from-list
+						(mapcar #'(lambda (p)
+									  (biome-char (patch-biome p)))
+							row) "")))))
+	
+	(defun coord (x y)
+		"Return the patch at the given coordinates or NIL if out of bounds"
+		(unless (or (< x 0) (< y 0) (> x (length world)) (> y (length world)))
+			(nth x (nth y world)))))
+
+;;; BIOMES
+
+(let ((biome-list NIL))
+	(defun register-biome (symbol-name biome-object)
+		(setf biome-list (cons (list symbol-name biome-object) biome-list)))
+
+	(defun available-biomes ()
+		(keys biome-list))
+
+	(defun get-biome (symbol-name)
+		(cassoc symbol-name biome-list)))
+
+(defmacro new-biome (name &body body)
+	`(register-biome ',name
+		 (make-biome
+			 :name ,(symbol-to-string name)
+			 ,@body)))
+
+;;; ITEMS
+
+(let ((item-list NIL))
+	(defun register-item (symbol-name item-object)
+		(setf item-list
+			(cons (list symbol-name item-object) item-list)))
+
+	(defun get-item-type (symbol-name)
+		(cassoc symbol-name item-list))
+
+	(defun get-item (symbol-name)
+		;;FIXME copy-item doesn't work with CLOS
+		(copy-item (get-item-type symbol-name))))
+
+(defmacro new-item (type name &body body)
+	`(register-item ',name
+		 (make-instance ',type
+			 :name ,(symbol-to-string name)
+			 ,@body)))
+
+;;; ANIMALS & SPECIES
+
+(let ((species-list NIL))
+	(defun register-species (symbol-name species-object)
+		(setf species-list
+			(cons (list symbol-name species-object) species-list)))
+
+	(defun get-species (symbol-name)
+		(cassoc symbol-name species-list)))
+
+(defmacro new-species (name &body body)
+	`(register-species ',name
+		 (make-instance 'species
+			 :name ,(symbol-to-string name)
+			 ,@body)))
+
+(let ((max-id 0) (animals NIL))
+	(defun add-animal (species position)
+		"Create a new animal of the given species"
+		(let ((a (make-animal :id max-id
+					 :pos position :species species
+					 :health (.max-health species))))
+			(incf max-id)
+			(setf animals (append animals a))))
+
+	(defun get-animal (id)
+		"Return the animal with this ID number"
+		(dolist (a animals)
+			(when (= (.id a) id)
+				(return-from get-animal a))))
+
+	(defun remove-animal (id)
+		"Remove the animal with this ID from the game"
+		(do ((al animals (cdr al)))
+			((null al))
+			(when (= (.id (car al)) id)
+				(setf (cdr al) (cddr al))))))

diff --git a/animals.lisp b/animals.lisp
index 09ac297..3f5634c 100644
--- a/animals.lisp
+++ b/animals.lisp
@@ -8,58 +8,28 @@
 ;;;; (c) 2018 Daniel Vedder, MIT license
 ;;;;
 
+;;TODO Change to African species
+;;XXX bird species?
 
-(defvar *animals* NIL)
-
-(let ((species-list NIL))
-	(defun register-species (symbol-name species-object)
-		(setf species-list
-			(cons (list symbol-name species-object) species-list)))
-
-	(defun get-species (symbol-name)
-		(cassoc symbol-name species-list)))
-
-(defmacro new-species (name &body body)
-	`(register-species ,name
-		 (make-instance 'species ,@body)))
-
-(let ((max-id 0))
-	(defun add-animal (species position)
-		"Create a new animal of the given species"
-		(let ((a (make-animal :id max-id
-					 :pos position :species species
-					 :health (.max-health species))))
-			(incf max-id)
-			(setf *animals* (append *animals* a)))))
-
-;;; SPECIES DEFINITIONS
-
-;;XXX Change to African species?
-;;TODO bird species
-
-(new-species 'deer
-	:name "deer"
+(new-species deer
 	:strength 3 :max-health 10 :aggression 0
 	:group-size 10
 	:habitat '(forest grassland)
 	:drops NIL) ;TODO
 
-(new-species 'boar
-	:name "boar"
+(new-species boar
 	:strength 7 :max-health 15 :aggression 5
 	:group-size 5
 	:habitat '(forest)
 	:drops NIL) ;TODO
 
-(new-species 'wolf
-	:name "wolf"
+(new-species wolf
 	:strength 10 :max-health 20 :aggression 20
 	:group-size 6
 	:habitat '(grassland)
 	:drops NIL) ;TODO
 
-(new-species 'bear
-	:name "bear"
+(new-species bear
 	:strength 20 :max-health 30 :aggression 20
 	:group-size 1
 	:habitat '(forest)
diff --git a/biomes.lisp b/biomes.lisp
index a723d8d..88d76c0 100644
--- a/biomes.lisp
+++ b/biomes.lisp
@@ -3,39 +3,11 @@
 ;;;; set in Africa.
 ;;;;
 ;;;; Biomes are habitat types, that provide default functions for patches.
-;;;; This file defines the biome struct and the inbuilt biomes.
+;;;; This file holds the biome definitions.
 ;;;; 
 ;;;; (c) 2018 Daniel Vedder, MIT license
 ;;;;
 
-;; Biome struct and register
-
-(defstruct biome
-	(name "")
-	(ground "")
-	(features '()) ;an alist of possible features and their 1/p probabilities
-	(char #\.) ;default map display character
-	(col ':white)) ;default map display colour
-
-(let ((biome-list NIL))
-	(defun register-biome (symbol-name biome-object)
-		(setf biome-list (cons (list symbol-name biome-object) biome-list)))
-
-	(defun available-biomes ()
-		(keys biome-list))
-
-	(defun get-biome (symbol-name)
-		(cassoc symbol-name biome-list)))
-
-(defmacro new-biome (name &body body)
-	`(register-biome ',name
-		 (make-biome
-			 :name ,(symbol-to-string name)
-			 ,@body)))
-
-
-;; Biome definitions
-
 (new-biome grassland
 	:ground "tall elephant grass"
 	:char #\; :col ':yellow
diff --git a/classes.lisp b/classes.lisp
index d559409..d30eb90 100644
--- a/classes.lisp
+++ b/classes.lisp
@@ -7,6 +7,7 @@
 ;;;; (c) 2018 Daniel Vedder, MIT license
 ;;;;
 
+
 (defclass item ()
 	;; The base class of all game items.
 	((name :accessor .name :initarg :name :initform "")
diff --git a/data.lisp b/data.lisp
new file mode 100644
index 0000000..23d9e39
--- /dev/null
+++ b/data.lisp
@@ -0,0 +1,107 @@
+;;;;
+;;;; Naledi ya Africa ("Star of Africa") is a rogue-like survival game
+;;;; set in Africa.
+;;;;
+;;;; This file stores all game data.
+;;;;
+;;;; (c) 2018 Daniel Vedder, MIT license
+;;;;
+
+;;; PATCHES
+
+(let ((world NIL))
+	(defun set-world (w) (setf world w))
+
+	(defun world-size () (length world))
+
+	(defun save-topography (file-name) ;XXX (re)move this?
+		"Save the world topography as a text file"
+		(debugging "~&Saving world to file ~A" file-name) ;debug
+		(with-open-file (tf file-name :direction :output)
+			(dolist (row world)
+				(format stream "~&~A~%"
+					(string-from-list
+						(mapcar #'(lambda (p)
+									  (biome-char (patch-biome p)))
+							row) "")))))
+	
+	(defun coord (x y)
+		"Return the patch at the given coordinates or NIL if out of bounds"
+		(unless (or (< x 0) (< y 0) (> x (length world)) (> y (length world)))
+			(nth x (nth y world)))))
+
+;;; BIOMES
+
+(let ((biome-list NIL))
+	(defun register-biome (symbol-name biome-object)
+		(setf biome-list (cons (list symbol-name biome-object) biome-list)))
+
+	(defun available-biomes ()
+		(keys biome-list))
+
+	(defun get-biome (symbol-name)
+		(cassoc symbol-name biome-list)))
+
+(defmacro new-biome (name &body body)
+	`(register-biome ',name
+		 (make-biome
+			 :name ,(symbol-to-string name)
+			 ,@body)))
+
+;;; ITEMS
+
+(let ((item-list NIL))
+	(defun register-item (symbol-name item-object)
+		(setf item-list
+			(cons (list symbol-name item-object) item-list)))
+
+	(defun get-item-type (symbol-name)
+		(cassoc symbol-name item-list))
+
+	(defun get-item (symbol-name)
+		;;FIXME copy-item doesn't work with CLOS
+		(copy-item (get-item-type symbol-name))))
+
+(defmacro new-item (type name &body body)
+	`(register-item ',name
+		 (make-instance ',type
+			 :name ,(symbol-to-string name)
+			 ,@body)))
+
+;;; ANIMALS & SPECIES
+
+(let ((species-list NIL))
+	(defun register-species (symbol-name species-object)
+		(setf species-list
+			(cons (list symbol-name species-object) species-list)))
+
+	(defun get-species (symbol-name)
+		(cassoc symbol-name species-list)))
+
+(defmacro new-species (name &body body)
+	`(register-species ',name
+		 (make-instance 'species
+			 :name ,(symbol-to-string name)
+			 ,@body)))
+
+(let ((max-id 0) (animals NIL))
+	(defun add-animal (species position)
+		"Create a new animal of the given species"
+		(let ((a (make-animal :id max-id
+					 :pos position :species species
+					 :health (.max-health species))))
+			(incf max-id)
+			(setf animals (append animals a))))
+
+	(defun get-animal (id)
+		"Return the animal with this ID number"
+		(dolist (a animals)
+			(when (= (.id a) id)
+				(return-from get-animal a))))
+
+	(defun remove-animal (id)
+		"Remove the animal with this ID from the game"
+		(do ((al animals (cdr al)))
+			((null al))
+			(when (= (.id (car al)) id)
+				(setf (cdr al) (cddr al))))))
diff --git a/items.lisp b/items.lisp
index 70e8acb..6957112 100644
--- a/items.lisp
+++ b/items.lisp
@@ -7,24 +7,6 @@
 ;;;; (c) 2018 Daniel Vedder, MIT license
 ;;;;
 
-(let ((item-list NIL))
-	(defun register-item (symbol-name item-object)
-		(setf item-list
-			(cons (list symbol-name item-object) item-list)))
-
-	(defun get-item-type (symbol-name)
-		(cassoc symbol-name item-list))
-
-	(defun get-item (symbol-name)
-		;;FIXME copy-item doesn't work with CLOS
-		(copy-item (get-item-type symbol-name))))
-
-(defmacro new-item (type name &body body)
-	`(register-item ',name
-		 (make-instance ',type
-			 :name ,(symbol-to-string name)
-			 ,@body)))
-
 
 ;;; RESOURCE ITEMS
 

diff --git a/animals.lisp b/animals.lisp
index 09ac297..3f5634c 100644
--- a/animals.lisp
+++ b/animals.lisp
@@ -8,58 +8,28 @@
 ;;;; (c) 2018 Daniel Vedder, MIT license
 ;;;;
 
+;;TODO Change to African species
+;;XXX bird species?
 
-(defvar *animals* NIL)
-
-(let ((species-list NIL))
-	(defun register-species (symbol-name species-object)
-		(setf species-list
-			(cons (list symbol-name species-object) species-list)))
-
-	(defun get-species (symbol-name)
-		(cassoc symbol-name species-list)))
-
-(defmacro new-species (name &body body)
-	`(register-species ,name
-		 (make-instance 'species ,@body)))
-
-(let ((max-id 0))
-	(defun add-animal (species position)
-		"Create a new animal of the given species"
-		(let ((a (make-animal :id max-id
-					 :pos position :species species
-					 :health (.max-health species))))
-			(incf max-id)
-			(setf *animals* (append *animals* a)))))
-
-;;; SPECIES DEFINITIONS
-
-;;XXX Change to African species?
-;;TODO bird species
-
-(new-species 'deer
-	:name "deer"
+(new-species deer
 	:strength 3 :max-health 10 :aggression 0
 	:group-size 10
 	:habitat '(forest grassland)
 	:drops NIL) ;TODO
 
-(new-species 'boar
-	:name "boar"
+(new-species boar
 	:strength 7 :max-health 15 :aggression 5
 	:group-size 5
 	:habitat '(forest)
 	:drops NIL) ;TODO
 
-(new-species 'wolf
-	:name "wolf"
+(new-species wolf
 	:strength 10 :max-health 20 :aggression 20
 	:group-size 6
 	:habitat '(grassland)
 	:drops NIL) ;TODO
 
-(new-species 'bear
-	:name "bear"
+(new-species bear
 	:strength 20 :max-health 30 :aggression 20
 	:group-size 1
 	:habitat '(forest)
diff --git a/biomes.lisp b/biomes.lisp
index a723d8d..88d76c0 100644
--- a/biomes.lisp
+++ b/biomes.lisp
@@ -3,39 +3,11 @@
 ;;;; set in Africa.
 ;;;;
 ;;;; Biomes are habitat types, that provide default functions for patches.
-;;;; This file defines the biome struct and the inbuilt biomes.
+;;;; This file holds the biome definitions.
 ;;;; 
 ;;;; (c) 2018 Daniel Vedder, MIT license
 ;;;;
 
-;; Biome struct and register
-
-(defstruct biome
-	(name "")
-	(ground "")
-	(features '()) ;an alist of possible features and their 1/p probabilities
-	(char #\.) ;default map display character
-	(col ':white)) ;default map display colour
-
-(let ((biome-list NIL))
-	(defun register-biome (symbol-name biome-object)
-		(setf biome-list (cons (list symbol-name biome-object) biome-list)))
-
-	(defun available-biomes ()
-		(keys biome-list))
-
-	(defun get-biome (symbol-name)
-		(cassoc symbol-name biome-list)))
-
-(defmacro new-biome (name &body body)
-	`(register-biome ',name
-		 (make-biome
-			 :name ,(symbol-to-string name)
-			 ,@body)))
-
-
-;; Biome definitions
-
 (new-biome grassland
 	:ground "tall elephant grass"
 	:char #\; :col ':yellow
diff --git a/classes.lisp b/classes.lisp
index d559409..d30eb90 100644
--- a/classes.lisp
+++ b/classes.lisp
@@ -7,6 +7,7 @@
 ;;;; (c) 2018 Daniel Vedder, MIT license
 ;;;;
 
+
 (defclass item ()
 	;; The base class of all game items.
 	((name :accessor .name :initarg :name :initform "")
diff --git a/data.lisp b/data.lisp
new file mode 100644
index 0000000..23d9e39
--- /dev/null
+++ b/data.lisp
@@ -0,0 +1,107 @@
+;;;;
+;;;; Naledi ya Africa ("Star of Africa") is a rogue-like survival game
+;;;; set in Africa.
+;;;;
+;;;; This file stores all game data.
+;;;;
+;;;; (c) 2018 Daniel Vedder, MIT license
+;;;;
+
+;;; PATCHES
+
+(let ((world NIL))
+	(defun set-world (w) (setf world w))
+
+	(defun world-size () (length world))
+
+	(defun save-topography (file-name) ;XXX (re)move this?
+		"Save the world topography as a text file"
+		(debugging "~&Saving world to file ~A" file-name) ;debug
+		(with-open-file (tf file-name :direction :output)
+			(dolist (row world)
+				(format stream "~&~A~%"
+					(string-from-list
+						(mapcar #'(lambda (p)
+									  (biome-char (patch-biome p)))
+							row) "")))))
+	
+	(defun coord (x y)
+		"Return the patch at the given coordinates or NIL if out of bounds"
+		(unless (or (< x 0) (< y 0) (> x (length world)) (> y (length world)))
+			(nth x (nth y world)))))
+
+;;; BIOMES
+
+(let ((biome-list NIL))
+	(defun register-biome (symbol-name biome-object)
+		(setf biome-list (cons (list symbol-name biome-object) biome-list)))
+
+	(defun available-biomes ()
+		(keys biome-list))
+
+	(defun get-biome (symbol-name)
+		(cassoc symbol-name biome-list)))
+
+(defmacro new-biome (name &body body)
+	`(register-biome ',name
+		 (make-biome
+			 :name ,(symbol-to-string name)
+			 ,@body)))
+
+;;; ITEMS
+
+(let ((item-list NIL))
+	(defun register-item (symbol-name item-object)
+		(setf item-list
+			(cons (list symbol-name item-object) item-list)))
+
+	(defun get-item-type (symbol-name)
+		(cassoc symbol-name item-list))
+
+	(defun get-item (symbol-name)
+		;;FIXME copy-item doesn't work with CLOS
+		(copy-item (get-item-type symbol-name))))
+
+(defmacro new-item (type name &body body)
+	`(register-item ',name
+		 (make-instance ',type
+			 :name ,(symbol-to-string name)
+			 ,@body)))
+
+;;; ANIMALS & SPECIES
+
+(let ((species-list NIL))
+	(defun register-species (symbol-name species-object)
+		(setf species-list
+			(cons (list symbol-name species-object) species-list)))
+
+	(defun get-species (symbol-name)
+		(cassoc symbol-name species-list)))
+
+(defmacro new-species (name &body body)
+	`(register-species ',name
+		 (make-instance 'species
+			 :name ,(symbol-to-string name)
+			 ,@body)))
+
+(let ((max-id 0) (animals NIL))
+	(defun add-animal (species position)
+		"Create a new animal of the given species"
+		(let ((a (make-animal :id max-id
+					 :pos position :species species
+					 :health (.max-health species))))
+			(incf max-id)
+			(setf animals (append animals a))))
+
+	(defun get-animal (id)
+		"Return the animal with this ID number"
+		(dolist (a animals)
+			(when (= (.id a) id)
+				(return-from get-animal a))))
+
+	(defun remove-animal (id)
+		"Remove the animal with this ID from the game"
+		(do ((al animals (cdr al)))
+			((null al))
+			(when (= (.id (car al)) id)
+				(setf (cdr al) (cddr al))))))
diff --git a/items.lisp b/items.lisp
index 70e8acb..6957112 100644
--- a/items.lisp
+++ b/items.lisp
@@ -7,24 +7,6 @@
 ;;;; (c) 2018 Daniel Vedder, MIT license
 ;;;;
 
-(let ((item-list NIL))
-	(defun register-item (symbol-name item-object)
-		(setf item-list
-			(cons (list symbol-name item-object) item-list)))
-
-	(defun get-item-type (symbol-name)
-		(cassoc symbol-name item-list))
-
-	(defun get-item (symbol-name)
-		;;FIXME copy-item doesn't work with CLOS
-		(copy-item (get-item-type symbol-name))))
-
-(defmacro new-item (type name &body body)
-	`(register-item ',name
-		 (make-instance ',type
-			 :name ,(symbol-to-string name)
-			 ,@body)))
-
 
 ;;; RESOURCE ITEMS
 
diff --git a/naledi.lisp b/naledi.lisp
index f7319f2..81b2d0a 100644
--- a/naledi.lisp
+++ b/naledi.lisp
@@ -15,10 +15,11 @@
 
 (load "util.lisp")
 (load "classes.lisp")
+(load "data.lisp")
+(load "world.lisp")
 (load "items.lisp")
 (load "biomes.lisp")
 (load "animals.lisp")
-(load "world.lisp")
 
 
 (defun user-interface ()
@@ -105,6 +106,7 @@
 
 (defun draw-place-panel (win me)
 	"Draw a panel with information about the player's current location."
+	(debugging "~&~S" me)
 	(let* ((p (coord (first me) (second me))) (descr (describe-patch p)))
 		(clear win)
 		(box win)
@@ -153,5 +155,5 @@
 ;; Initialize the random state (which would otherwise not be very random...)
 (setf *random-state* (make-random-state t))
 
-(setf *world* (create-world 500))
+(create-world 100)
 (user-interface)

diff --git a/animals.lisp b/animals.lisp
index 09ac297..3f5634c 100644
--- a/animals.lisp
+++ b/animals.lisp
@@ -8,58 +8,28 @@
 ;;;; (c) 2018 Daniel Vedder, MIT license
 ;;;;
 
+;;TODO Change to African species
+;;XXX bird species?
 
-(defvar *animals* NIL)
-
-(let ((species-list NIL))
-	(defun register-species (symbol-name species-object)
-		(setf species-list
-			(cons (list symbol-name species-object) species-list)))
-
-	(defun get-species (symbol-name)
-		(cassoc symbol-name species-list)))
-
-(defmacro new-species (name &body body)
-	`(register-species ,name
-		 (make-instance 'species ,@body)))
-
-(let ((max-id 0))
-	(defun add-animal (species position)
-		"Create a new animal of the given species"
-		(let ((a (make-animal :id max-id
-					 :pos position :species species
-					 :health (.max-health species))))
-			(incf max-id)
-			(setf *animals* (append *animals* a)))))
-
-;;; SPECIES DEFINITIONS
-
-;;XXX Change to African species?
-;;TODO bird species
-
-(new-species 'deer
-	:name "deer"
+(new-species deer
 	:strength 3 :max-health 10 :aggression 0
 	:group-size 10
 	:habitat '(forest grassland)
 	:drops NIL) ;TODO
 
-(new-species 'boar
-	:name "boar"
+(new-species boar
 	:strength 7 :max-health 15 :aggression 5
 	:group-size 5
 	:habitat '(forest)
 	:drops NIL) ;TODO
 
-(new-species 'wolf
-	:name "wolf"
+(new-species wolf
 	:strength 10 :max-health 20 :aggression 20
 	:group-size 6
 	:habitat '(grassland)
 	:drops NIL) ;TODO
 
-(new-species 'bear
-	:name "bear"
+(new-species bear
 	:strength 20 :max-health 30 :aggression 20
 	:group-size 1
 	:habitat '(forest)
diff --git a/biomes.lisp b/biomes.lisp
index a723d8d..88d76c0 100644
--- a/biomes.lisp
+++ b/biomes.lisp
@@ -3,39 +3,11 @@
 ;;;; set in Africa.
 ;;;;
 ;;;; Biomes are habitat types, that provide default functions for patches.
-;;;; This file defines the biome struct and the inbuilt biomes.
+;;;; This file holds the biome definitions.
 ;;;; 
 ;;;; (c) 2018 Daniel Vedder, MIT license
 ;;;;
 
-;; Biome struct and register
-
-(defstruct biome
-	(name "")
-	(ground "")
-	(features '()) ;an alist of possible features and their 1/p probabilities
-	(char #\.) ;default map display character
-	(col ':white)) ;default map display colour
-
-(let ((biome-list NIL))
-	(defun register-biome (symbol-name biome-object)
-		(setf biome-list (cons (list symbol-name biome-object) biome-list)))
-
-	(defun available-biomes ()
-		(keys biome-list))
-
-	(defun get-biome (symbol-name)
-		(cassoc symbol-name biome-list)))
-
-(defmacro new-biome (name &body body)
-	`(register-biome ',name
-		 (make-biome
-			 :name ,(symbol-to-string name)
-			 ,@body)))
-
-
-;; Biome definitions
-
 (new-biome grassland
 	:ground "tall elephant grass"
 	:char #\; :col ':yellow
diff --git a/classes.lisp b/classes.lisp
index d559409..d30eb90 100644
--- a/classes.lisp
+++ b/classes.lisp
@@ -7,6 +7,7 @@
 ;;;; (c) 2018 Daniel Vedder, MIT license
 ;;;;
 
+
 (defclass item ()
 	;; The base class of all game items.
 	((name :accessor .name :initarg :name :initform "")
diff --git a/data.lisp b/data.lisp
new file mode 100644
index 0000000..23d9e39
--- /dev/null
+++ b/data.lisp
@@ -0,0 +1,107 @@
+;;;;
+;;;; Naledi ya Africa ("Star of Africa") is a rogue-like survival game
+;;;; set in Africa.
+;;;;
+;;;; This file stores all game data.
+;;;;
+;;;; (c) 2018 Daniel Vedder, MIT license
+;;;;
+
+;;; PATCHES
+
+(let ((world NIL))
+	(defun set-world (w) (setf world w))
+
+	(defun world-size () (length world))
+
+	(defun save-topography (file-name) ;XXX (re)move this?
+		"Save the world topography as a text file"
+		(debugging "~&Saving world to file ~A" file-name) ;debug
+		(with-open-file (tf file-name :direction :output)
+			(dolist (row world)
+				(format stream "~&~A~%"
+					(string-from-list
+						(mapcar #'(lambda (p)
+									  (biome-char (patch-biome p)))
+							row) "")))))
+	
+	(defun coord (x y)
+		"Return the patch at the given coordinates or NIL if out of bounds"
+		(unless (or (< x 0) (< y 0) (> x (length world)) (> y (length world)))
+			(nth x (nth y world)))))
+
+;;; BIOMES
+
+(let ((biome-list NIL))
+	(defun register-biome (symbol-name biome-object)
+		(setf biome-list (cons (list symbol-name biome-object) biome-list)))
+
+	(defun available-biomes ()
+		(keys biome-list))
+
+	(defun get-biome (symbol-name)
+		(cassoc symbol-name biome-list)))
+
+(defmacro new-biome (name &body body)
+	`(register-biome ',name
+		 (make-biome
+			 :name ,(symbol-to-string name)
+			 ,@body)))
+
+;;; ITEMS
+
+(let ((item-list NIL))
+	(defun register-item (symbol-name item-object)
+		(setf item-list
+			(cons (list symbol-name item-object) item-list)))
+
+	(defun get-item-type (symbol-name)
+		(cassoc symbol-name item-list))
+
+	(defun get-item (symbol-name)
+		;;FIXME copy-item doesn't work with CLOS
+		(copy-item (get-item-type symbol-name))))
+
+(defmacro new-item (type name &body body)
+	`(register-item ',name
+		 (make-instance ',type
+			 :name ,(symbol-to-string name)
+			 ,@body)))
+
+;;; ANIMALS & SPECIES
+
+(let ((species-list NIL))
+	(defun register-species (symbol-name species-object)
+		(setf species-list
+			(cons (list symbol-name species-object) species-list)))
+
+	(defun get-species (symbol-name)
+		(cassoc symbol-name species-list)))
+
+(defmacro new-species (name &body body)
+	`(register-species ',name
+		 (make-instance 'species
+			 :name ,(symbol-to-string name)
+			 ,@body)))
+
+(let ((max-id 0) (animals NIL))
+	(defun add-animal (species position)
+		"Create a new animal of the given species"
+		(let ((a (make-animal :id max-id
+					 :pos position :species species
+					 :health (.max-health species))))
+			(incf max-id)
+			(setf animals (append animals a))))
+
+	(defun get-animal (id)
+		"Return the animal with this ID number"
+		(dolist (a animals)
+			(when (= (.id a) id)
+				(return-from get-animal a))))
+
+	(defun remove-animal (id)
+		"Remove the animal with this ID from the game"
+		(do ((al animals (cdr al)))
+			((null al))
+			(when (= (.id (car al)) id)
+				(setf (cdr al) (cddr al))))))
diff --git a/items.lisp b/items.lisp
index 70e8acb..6957112 100644
--- a/items.lisp
+++ b/items.lisp
@@ -7,24 +7,6 @@
 ;;;; (c) 2018 Daniel Vedder, MIT license
 ;;;;
 
-(let ((item-list NIL))
-	(defun register-item (symbol-name item-object)
-		(setf item-list
-			(cons (list symbol-name item-object) item-list)))
-
-	(defun get-item-type (symbol-name)
-		(cassoc symbol-name item-list))
-
-	(defun get-item (symbol-name)
-		;;FIXME copy-item doesn't work with CLOS
-		(copy-item (get-item-type symbol-name))))
-
-(defmacro new-item (type name &body body)
-	`(register-item ',name
-		 (make-instance ',type
-			 :name ,(symbol-to-string name)
-			 ,@body)))
-
 
 ;;; RESOURCE ITEMS
 
diff --git a/naledi.lisp b/naledi.lisp
index f7319f2..81b2d0a 100644
--- a/naledi.lisp
+++ b/naledi.lisp
@@ -15,10 +15,11 @@
 
 (load "util.lisp")
 (load "classes.lisp")
+(load "data.lisp")
+(load "world.lisp")
 (load "items.lisp")
 (load "biomes.lisp")
 (load "animals.lisp")
-(load "world.lisp")
 
 
 (defun user-interface ()
@@ -105,6 +106,7 @@
 
 (defun draw-place-panel (win me)
 	"Draw a panel with information about the player's current location."
+	(debugging "~&~S" me)
 	(let* ((p (coord (first me) (second me))) (descr (describe-patch p)))
 		(clear win)
 		(box win)
@@ -153,5 +155,5 @@
 ;; Initialize the random state (which would otherwise not be very random...)
 (setf *random-state* (make-random-state t))
 
-(setf *world* (create-world 500))
+(create-world 100)
 (user-interface)
diff --git a/util.lisp b/util.lisp
index c50e0ce..d6d034c 100644
--- a/util.lisp
+++ b/util.lisp
@@ -96,6 +96,10 @@
 	(if (null assoc-list) NIL
 		(cons (car (car assoc-list)) (keys (cdr assoc-list)))))
 
+(defun build-symbol (&rest components)
+	"Concatenate the passed components into a single symbol"
+	(read-from-string (string-from-list components :sep "")))
+
 (defun symbol-to-string (sym)
 	"Convert a symbol to a string, exchanging dashes for spaces"
 	(string-from-list

diff --git a/animals.lisp b/animals.lisp
index 09ac297..3f5634c 100644
--- a/animals.lisp
+++ b/animals.lisp
@@ -8,58 +8,28 @@
 ;;;; (c) 2018 Daniel Vedder, MIT license
 ;;;;
 
+;;TODO Change to African species
+;;XXX bird species?
 
-(defvar *animals* NIL)
-
-(let ((species-list NIL))
-	(defun register-species (symbol-name species-object)
-		(setf species-list
-			(cons (list symbol-name species-object) species-list)))
-
-	(defun get-species (symbol-name)
-		(cassoc symbol-name species-list)))
-
-(defmacro new-species (name &body body)
-	`(register-species ,name
-		 (make-instance 'species ,@body)))
-
-(let ((max-id 0))
-	(defun add-animal (species position)
-		"Create a new animal of the given species"
-		(let ((a (make-animal :id max-id
-					 :pos position :species species
-					 :health (.max-health species))))
-			(incf max-id)
-			(setf *animals* (append *animals* a)))))
-
-;;; SPECIES DEFINITIONS
-
-;;XXX Change to African species?
-;;TODO bird species
-
-(new-species 'deer
-	:name "deer"
+(new-species deer
 	:strength 3 :max-health 10 :aggression 0
 	:group-size 10
 	:habitat '(forest grassland)
 	:drops NIL) ;TODO
 
-(new-species 'boar
-	:name "boar"
+(new-species boar
 	:strength 7 :max-health 15 :aggression 5
 	:group-size 5
 	:habitat '(forest)
 	:drops NIL) ;TODO
 
-(new-species 'wolf
-	:name "wolf"
+(new-species wolf
 	:strength 10 :max-health 20 :aggression 20
 	:group-size 6
 	:habitat '(grassland)
 	:drops NIL) ;TODO
 
-(new-species 'bear
-	:name "bear"
+(new-species bear
 	:strength 20 :max-health 30 :aggression 20
 	:group-size 1
 	:habitat '(forest)
diff --git a/biomes.lisp b/biomes.lisp
index a723d8d..88d76c0 100644
--- a/biomes.lisp
+++ b/biomes.lisp
@@ -3,39 +3,11 @@
 ;;;; set in Africa.
 ;;;;
 ;;;; Biomes are habitat types, that provide default functions for patches.
-;;;; This file defines the biome struct and the inbuilt biomes.
+;;;; This file holds the biome definitions.
 ;;;; 
 ;;;; (c) 2018 Daniel Vedder, MIT license
 ;;;;
 
-;; Biome struct and register
-
-(defstruct biome
-	(name "")
-	(ground "")
-	(features '()) ;an alist of possible features and their 1/p probabilities
-	(char #\.) ;default map display character
-	(col ':white)) ;default map display colour
-
-(let ((biome-list NIL))
-	(defun register-biome (symbol-name biome-object)
-		(setf biome-list (cons (list symbol-name biome-object) biome-list)))
-
-	(defun available-biomes ()
-		(keys biome-list))
-
-	(defun get-biome (symbol-name)
-		(cassoc symbol-name biome-list)))
-
-(defmacro new-biome (name &body body)
-	`(register-biome ',name
-		 (make-biome
-			 :name ,(symbol-to-string name)
-			 ,@body)))
-
-
-;; Biome definitions
-
 (new-biome grassland
 	:ground "tall elephant grass"
 	:char #\; :col ':yellow
diff --git a/classes.lisp b/classes.lisp
index d559409..d30eb90 100644
--- a/classes.lisp
+++ b/classes.lisp
@@ -7,6 +7,7 @@
 ;;;; (c) 2018 Daniel Vedder, MIT license
 ;;;;
 
+
 (defclass item ()
 	;; The base class of all game items.
 	((name :accessor .name :initarg :name :initform "")
diff --git a/data.lisp b/data.lisp
new file mode 100644
index 0000000..23d9e39
--- /dev/null
+++ b/data.lisp
@@ -0,0 +1,107 @@
+;;;;
+;;;; Naledi ya Africa ("Star of Africa") is a rogue-like survival game
+;;;; set in Africa.
+;;;;
+;;;; This file stores all game data.
+;;;;
+;;;; (c) 2018 Daniel Vedder, MIT license
+;;;;
+
+;;; PATCHES
+
+(let ((world NIL))
+	(defun set-world (w) (setf world w))
+
+	(defun world-size () (length world))
+
+	(defun save-topography (file-name) ;XXX (re)move this?
+		"Save the world topography as a text file"
+		(debugging "~&Saving world to file ~A" file-name) ;debug
+		(with-open-file (tf file-name :direction :output)
+			(dolist (row world)
+				(format stream "~&~A~%"
+					(string-from-list
+						(mapcar #'(lambda (p)
+									  (biome-char (patch-biome p)))
+							row) "")))))
+	
+	(defun coord (x y)
+		"Return the patch at the given coordinates or NIL if out of bounds"
+		(unless (or (< x 0) (< y 0) (> x (length world)) (> y (length world)))
+			(nth x (nth y world)))))
+
+;;; BIOMES
+
+(let ((biome-list NIL))
+	(defun register-biome (symbol-name biome-object)
+		(setf biome-list (cons (list symbol-name biome-object) biome-list)))
+
+	(defun available-biomes ()
+		(keys biome-list))
+
+	(defun get-biome (symbol-name)
+		(cassoc symbol-name biome-list)))
+
+(defmacro new-biome (name &body body)
+	`(register-biome ',name
+		 (make-biome
+			 :name ,(symbol-to-string name)
+			 ,@body)))
+
+;;; ITEMS
+
+(let ((item-list NIL))
+	(defun register-item (symbol-name item-object)
+		(setf item-list
+			(cons (list symbol-name item-object) item-list)))
+
+	(defun get-item-type (symbol-name)
+		(cassoc symbol-name item-list))
+
+	(defun get-item (symbol-name)
+		;;FIXME copy-item doesn't work with CLOS
+		(copy-item (get-item-type symbol-name))))
+
+(defmacro new-item (type name &body body)
+	`(register-item ',name
+		 (make-instance ',type
+			 :name ,(symbol-to-string name)
+			 ,@body)))
+
+;;; ANIMALS & SPECIES
+
+(let ((species-list NIL))
+	(defun register-species (symbol-name species-object)
+		(setf species-list
+			(cons (list symbol-name species-object) species-list)))
+
+	(defun get-species (symbol-name)
+		(cassoc symbol-name species-list)))
+
+(defmacro new-species (name &body body)
+	`(register-species ',name
+		 (make-instance 'species
+			 :name ,(symbol-to-string name)
+			 ,@body)))
+
+(let ((max-id 0) (animals NIL))
+	(defun add-animal (species position)
+		"Create a new animal of the given species"
+		(let ((a (make-animal :id max-id
+					 :pos position :species species
+					 :health (.max-health species))))
+			(incf max-id)
+			(setf animals (append animals a))))
+
+	(defun get-animal (id)
+		"Return the animal with this ID number"
+		(dolist (a animals)
+			(when (= (.id a) id)
+				(return-from get-animal a))))
+
+	(defun remove-animal (id)
+		"Remove the animal with this ID from the game"
+		(do ((al animals (cdr al)))
+			((null al))
+			(when (= (.id (car al)) id)
+				(setf (cdr al) (cddr al))))))
diff --git a/items.lisp b/items.lisp
index 70e8acb..6957112 100644
--- a/items.lisp
+++ b/items.lisp
@@ -7,24 +7,6 @@
 ;;;; (c) 2018 Daniel Vedder, MIT license
 ;;;;
 
-(let ((item-list NIL))
-	(defun register-item (symbol-name item-object)
-		(setf item-list
-			(cons (list symbol-name item-object) item-list)))
-
-	(defun get-item-type (symbol-name)
-		(cassoc symbol-name item-list))
-
-	(defun get-item (symbol-name)
-		;;FIXME copy-item doesn't work with CLOS
-		(copy-item (get-item-type symbol-name))))
-
-(defmacro new-item (type name &body body)
-	`(register-item ',name
-		 (make-instance ',type
-			 :name ,(symbol-to-string name)
-			 ,@body)))
-
 
 ;;; RESOURCE ITEMS
 
diff --git a/naledi.lisp b/naledi.lisp
index f7319f2..81b2d0a 100644
--- a/naledi.lisp
+++ b/naledi.lisp
@@ -15,10 +15,11 @@
 
 (load "util.lisp")
 (load "classes.lisp")
+(load "data.lisp")
+(load "world.lisp")
 (load "items.lisp")
 (load "biomes.lisp")
 (load "animals.lisp")
-(load "world.lisp")
 
 
 (defun user-interface ()
@@ -105,6 +106,7 @@
 
 (defun draw-place-panel (win me)
 	"Draw a panel with information about the player's current location."
+	(debugging "~&~S" me)
 	(let* ((p (coord (first me) (second me))) (descr (describe-patch p)))
 		(clear win)
 		(box win)
@@ -153,5 +155,5 @@
 ;; Initialize the random state (which would otherwise not be very random...)
 (setf *random-state* (make-random-state t))
 
-(setf *world* (create-world 500))
+(create-world 100)
 (user-interface)
diff --git a/util.lisp b/util.lisp
index c50e0ce..d6d034c 100644
--- a/util.lisp
+++ b/util.lisp
@@ -96,6 +96,10 @@
 	(if (null assoc-list) NIL
 		(cons (car (car assoc-list)) (keys (cdr assoc-list)))))
 
+(defun build-symbol (&rest components)
+	"Concatenate the passed components into a single symbol"
+	(read-from-string (string-from-list components :sep "")))
+
 (defun symbol-to-string (sym)
 	"Convert a symbol to a string, exchanging dashes for spaces"
 	(string-from-list
diff --git a/world.lisp b/world.lisp
index b591133..d46cdb6 100644
--- a/world.lisp
+++ b/world.lisp
@@ -7,7 +7,6 @@
 ;;;; (c) 2018 Daniel Vedder, MIT license
 ;;;;
 
-(defparameter *world* NIL)
 (defconstant *directions* '(N NE E SE S SW W NW))
 
 (defstruct patch
@@ -16,6 +15,14 @@
 	(items '())
 	(occupant NIL))
 
+(defstruct biome
+	(name "")
+	(ground "")
+	(features '()) ;an alist of possible features and their 1/p probabilities
+	(char #\.) ;default map display character
+	(col ':white)) ;default map display colour
+
+
 ;; MATRIX FUNCTIONS
 
 (defun init-matrix (size)
@@ -28,11 +35,6 @@
 			(setf row (append row (list (make-patch :pos (list x y))))))
 		(setf world (append world (list row)))))
 
-(defun coord (x y &optional (world *world*))
-	"Return the patch at the given coordinates or NIL if out of bounds"
-	(unless (or (< x 0) (< y 0) (> x (length world)) (> y (length world)))
-		(nth x (nth y world))))
-
 (defun distance (x1 y1 x2 y2 &optional (pythag NIL))
 	"Find the distance between two sets of coordinates"
 	(if pythag (round (sqrt (+ (expt (- x1 x2) 2) (expt (- y1 y2) 2))))
@@ -96,34 +98,15 @@
 		((null dir) (list x y))
 		(T (error "~&Invalid direction ~S"))))
 
-(defun patchindir (x y dir &optional (world *world*))
+(defun patchindir (x y dir)
 	"Return the patch in the given direction"
 	(let* ((coords (coordsindir x y dir))
 			  (nextx (first coords)) (nexty (second coords)))
-		(coord nextx nexty world)))
+		(coord nextx nexty)))
 
-(defun neighbour (p dir &optional (world *world*))
+(defun neighbour (p dir)
 	"Return the neighbouring patch in this direction"
-	(patchindir (first (patch-pos p)) (second (patch-pos p)) dir world))
-
-
-;; TOPOGRAPHY FUNCTIONS
-
-;;XXX Do I still need these?
-
-(defun print-topography (&optional (stream T) (world *world*))
-	"Print a text representation of the world and each patch's biome"
-	(dolist (row world)
-		(format stream "~&~A~%"
-			(string-from-list
-				(mapcar #'(lambda (p) (biome-char (patch-biome p))) row)
-				""))))
-
-(defun save-topography (file-name &optional (world *world*))
-	"Save the world topography as a text file"
-	(debugging "~&Saving world to file ~A" file-name) ;debug
-	(with-open-file (tf file-name :direction :output)
-		(print-topography tf)))
+	(patchindir (first (patch-pos p)) (second (patch-pos p)) dir))
 
 
 ;; WORLD CREATION FUNCTIONS
@@ -135,36 +118,36 @@
 			(when (chancep (second f))
 				(return-from get-patch-feature (get-item-type (first f)))))))
 
-(defun generate-biomes (size-factor world)
+(defun generate-biomes (size-factor)
 	;;XXX The maps this produces don't look quite as expected, but for
 	;; current purposes they are good enough
 	(debugging "~&Generating biomes") ;debug
-	(let* ((world-size (length world)) (seeds NIL)
-			  (nseeds (round (/ world-size size-factor)))
+	(let* ((wsize (world-size)) (seeds NIL)
+			  (nseeds (round (/ wsize size-factor)))
 			  (biomes (remove-first-if
 						  #'(lambda (e) (eq e 'stream))
 						  (available-biomes))))
 		;;Initialize a set of biome 'seed' coordinates
 		(dotimes (n nseeds)
 			(setf seeds
-				(cons (list (random world-size)
-						  (random world-size)
+				(cons (list (random wsize)
+						  (random wsize)
 						  (random-elt biomes))
 					seeds)))
 		(debugging "~&~S" seeds)
 		;;For each patch, calculate the closest seed and set to that biome
-		(dotimes (x world-size)
-			(dotimes (y world-size)
-				(let ((p (coord x y world))
+		(dotimes (x wsize)
+			(dotimes (y wsize)
+				(let ((p (coord x y))
 						 (b (third (closest-coords (list x y) seeds T))))
 					(setf (patch-biome p) (get-biome b))
 					(setf (patch-occupant p) (get-patch-feature p)))))))
 	
-(defun generate-stream (x0 y0 world)
+(defun generate-stream (x0 y0)
 	(debugging "~&Generating a stream, starting at ~S/~S" x0 y0) ;debug
 	(do* ((dir (random-elt *directions*)
 			  (if (probabilityp 75) dir (next-dir dir (random-elt '(T NIL)))))
-			 (patch (coord x0 y0 world) (neighbour patch dir world)))
+			 (patch (coord x0 y0) (neighbour patch dir)))
 		((or (null patch) (eq (patch-biome patch) (get-biome 'stream))))
 		(setf (patch-biome patch) (get-biome 'stream))
 		(setf (patch-occupant patch) NIL)))
@@ -172,14 +155,13 @@
 ;;TODO create animal herds
 
 (defun create-world (size)
-	(let ((world (init-matrix size)))
-		;;XXX magic numbers
-		(generate-biomes 10 world)
-		(dotimes (s (round (/ (expt size 2) 2000)))
-			(generate-stream (random size) (random size) world))
-		world))
+	(set-world (init-matrix size))
+	;;XXX magic numbers
+	(generate-biomes 10)
+	(dotimes (s (round (/ (expt size 2) 2000)))
+		(generate-stream (random size) (random size))))
 
-(defun describe-patch (p)
+(defun describe-patch (p) ;;FIXME needs a line width parameter
 	"Return a list of lines describing this patch."
     (list (string-upcase (biome-name (patch-biome p))) ""
 		(format NIL "~A / ~A" (first (patch-pos p)) (second (patch-pos p)))	""