diff --git a/biome.lisp b/biome.lisp
index 648452e..6be8217 100644
--- a/biome.lisp
+++ b/biome.lisp
@@ -59,3 +59,14 @@
 	:name "stream" :char #\~
 	:init-items NIL ;TODO
 	:update-fn #'update-stream)
+
+;; Hill biome
+
+(defun update-hill (patch-pos)
+	;;TODO
+	)
+
+(new-biome 'hill
+	:name "hill" :char #\m
+	:init-items NIL ;TODO
+	:update-fn #'update-hill)

diff --git a/biome.lisp b/biome.lisp
index 648452e..6be8217 100644
--- a/biome.lisp
+++ b/biome.lisp
@@ -59,3 +59,14 @@
 	:name "stream" :char #\~
 	:init-items NIL ;TODO
 	:update-fn #'update-stream)
+
+;; Hill biome
+
+(defun update-hill (patch-pos)
+	;;TODO
+	)
+
+(new-biome 'hill
+	:name "hill" :char #\m
+	:init-items NIL ;TODO
+	:update-fn #'update-hill)
diff --git a/terranostra.lisp b/terranostra.lisp
index 1377574..7771626 100644
--- a/terranostra.lisp
+++ b/terranostra.lisp
@@ -1,19 +1,25 @@
 ;#!/usr/bin/clisp
 ;;;;
 ;;;; Terra Nostra is a Minecraft-like survival game for the commandline.
-;;;; 
+;;;;
+;;;; This file defines patches and administrates the world object.
+;;;;
 ;;;; (c) 2018 Daniel Vedder, MIT license
 ;;;;
 
-(load "util.lisp") ;; I want to avoid using this if possible
+(load "util.lisp")
+(load "items.lisp")
 (load "biome.lisp")
+(load "animals.lisp")
 
 (defvar *world* NIL)
 (defconstant *directions* '(N NE E SE S SW W NW))
 
 (defstruct patch
 	(pos '(0 0)) ;position
-	(biome (make-biome)))
+	(biome (get-biome 'grassland))
+	(items '())
+	(animals '()))
 
 
 (defun init-matrix (size)
@@ -35,6 +41,12 @@
 	(let ((pos (position dir *directions*)))
 		(when pos (nth (rem (+ 4 pos) 8) *directions*))))
 
+(defun next-dir (dir &optional (cw T))
+	"Get the neighbouring direction (clockwise or anticlockwise)"
+	(let ((pos (position dir *directions*))
+			 (diff (if cw 1 -1)))
+		(when pos (nth (rem (+ diff pos 8) 8) *directions*))))
+
 (defun dir2patch (herex herey therex therey)
 	"Calculate the direction to a patch"
 	(cond ((> herex therex)
@@ -76,19 +88,38 @@
 	"Save the world topography as a csv file"
 	(with-open-file (tf file-name :direction :output)
 		(dolist (row world)
-			;; XXX This would be quicker with (string-from-list), but I
-			;; don't want to use util.lisp just yet
+			;; TODO This would be quicker with (string-from-list)
 			(do ((x 0 (1+ x)) (xstr ""))
 				((= x (length world)) (format tf "~&~A~%" xstr))
-				;;TODO
 				(setf xstr (concatenate 'string xstr (unless (= x 0) ",")
 							   (format NIL "~S"
 								   (biome-char (patch-biome (nth x row))))))))))
 
 
-(defun create-world (size name &optional (world *world*))
+(defun generate-biome-patch (biome-type x y width &optional (world *world*))
+	;;TODO
+	)
+
+(defun generate-stream (x0 y0 &optional (world *world*))
+	(do* ((dir (random-elt *directions*)
+			  (if (chancep 60) dir (next-dir dir (random-elt '(T NIL)))))
+			 (patch (coord x0 y0) (neighbour patch dir)))
+		((or (null patch) (eq (patch-biome patch) (get-biome 'stream))))
+		(setf (patch-biome patch) (get-biome 'stream))))
+
+(defun create-world (size name &optional (world *world*)
+						(biomes '(forest hill)) (size-factor 30))
 	(setf world NIL)
 	(setf world (init-matrix size))
+	;;XXX magic numbers
+	(dotimes (s (round (/ (expt size 2) (* size-factor 10))))
+		(generate-stream (random size) (random size) world))
+	(dotimes (f (round (/ (expt size 2) (expt size-factor 2))))
+		(generate-biome-patch 'forest (random size) (random size)
+			(random size-factor) world))
+	(dotimes (h (round (/ (expt size 2) (* 1.5 (expt size-factor 2)))))
+		(generate-biome-patch 'hill (random size) (random size)
+			(random (round (/ 2 size-factor))) world))
 	;;TODO
 	(save-topography name world))
 

diff --git a/biome.lisp b/biome.lisp
index 648452e..6be8217 100644
--- a/biome.lisp
+++ b/biome.lisp
@@ -59,3 +59,14 @@
 	:name "stream" :char #\~
 	:init-items NIL ;TODO
 	:update-fn #'update-stream)
+
+;; Hill biome
+
+(defun update-hill (patch-pos)
+	;;TODO
+	)
+
+(new-biome 'hill
+	:name "hill" :char #\m
+	:init-items NIL ;TODO
+	:update-fn #'update-hill)
diff --git a/terranostra.lisp b/terranostra.lisp
index 1377574..7771626 100644
--- a/terranostra.lisp
+++ b/terranostra.lisp
@@ -1,19 +1,25 @@
 ;#!/usr/bin/clisp
 ;;;;
 ;;;; Terra Nostra is a Minecraft-like survival game for the commandline.
-;;;; 
+;;;;
+;;;; This file defines patches and administrates the world object.
+;;;;
 ;;;; (c) 2018 Daniel Vedder, MIT license
 ;;;;
 
-(load "util.lisp") ;; I want to avoid using this if possible
+(load "util.lisp")
+(load "items.lisp")
 (load "biome.lisp")
+(load "animals.lisp")
 
 (defvar *world* NIL)
 (defconstant *directions* '(N NE E SE S SW W NW))
 
 (defstruct patch
 	(pos '(0 0)) ;position
-	(biome (make-biome)))
+	(biome (get-biome 'grassland))
+	(items '())
+	(animals '()))
 
 
 (defun init-matrix (size)
@@ -35,6 +41,12 @@
 	(let ((pos (position dir *directions*)))
 		(when pos (nth (rem (+ 4 pos) 8) *directions*))))
 
+(defun next-dir (dir &optional (cw T))
+	"Get the neighbouring direction (clockwise or anticlockwise)"
+	(let ((pos (position dir *directions*))
+			 (diff (if cw 1 -1)))
+		(when pos (nth (rem (+ diff pos 8) 8) *directions*))))
+
 (defun dir2patch (herex herey therex therey)
 	"Calculate the direction to a patch"
 	(cond ((> herex therex)
@@ -76,19 +88,38 @@
 	"Save the world topography as a csv file"
 	(with-open-file (tf file-name :direction :output)
 		(dolist (row world)
-			;; XXX This would be quicker with (string-from-list), but I
-			;; don't want to use util.lisp just yet
+			;; TODO This would be quicker with (string-from-list)
 			(do ((x 0 (1+ x)) (xstr ""))
 				((= x (length world)) (format tf "~&~A~%" xstr))
-				;;TODO
 				(setf xstr (concatenate 'string xstr (unless (= x 0) ",")
 							   (format NIL "~S"
 								   (biome-char (patch-biome (nth x row))))))))))
 
 
-(defun create-world (size name &optional (world *world*))
+(defun generate-biome-patch (biome-type x y width &optional (world *world*))
+	;;TODO
+	)
+
+(defun generate-stream (x0 y0 &optional (world *world*))
+	(do* ((dir (random-elt *directions*)
+			  (if (chancep 60) dir (next-dir dir (random-elt '(T NIL)))))
+			 (patch (coord x0 y0) (neighbour patch dir)))
+		((or (null patch) (eq (patch-biome patch) (get-biome 'stream))))
+		(setf (patch-biome patch) (get-biome 'stream))))
+
+(defun create-world (size name &optional (world *world*)
+						(biomes '(forest hill)) (size-factor 30))
 	(setf world NIL)
 	(setf world (init-matrix size))
+	;;XXX magic numbers
+	(dotimes (s (round (/ (expt size 2) (* size-factor 10))))
+		(generate-stream (random size) (random size) world))
+	(dotimes (f (round (/ (expt size 2) (expt size-factor 2))))
+		(generate-biome-patch 'forest (random size) (random size)
+			(random size-factor) world))
+	(dotimes (h (round (/ (expt size 2) (* 1.5 (expt size-factor 2)))))
+		(generate-biome-patch 'hill (random size) (random size)
+			(random (round (/ 2 size-factor))) world))
 	;;TODO
 	(save-topography name world))
 
diff --git a/util.lisp b/util.lisp
index f3e68a4..baa2885 100644
--- a/util.lisp
+++ b/util.lisp
@@ -198,6 +198,10 @@
 	"Return a random element of this sequence"
 	(elt seq (random (length seq))))
 
+(defun chancep (percent)
+	"Do a random test, with the percentage giving the success probability"
+	(> percent (random 100)))
+
 (defun load-text-file (file-name)
 	"Load a text file into a list of strings (representing the lines)"
 	(with-open-file (f file-name)