four squares

to setup
  clear-all
  ask patches[set pcolor green]
  ask patches with[pxcor < 0 and pycor > 0][set pcolor black]
  ask patches with[pxcor > -1 and pycor >= 0][set pcolor blue]
  ask patches with[pxcor < 0 and pycor < 1][set pcolor red]
  ask patches with[pxcor > -1 and pycor <= 0][set pcolor yellow]
  ask patch 0 0 [ask patches in-radius 4 [set pcolor pink]]
  create-turtles 4
  ask turtles[setxy random-xcor random-ycor]
  ask turtles[set shape "turtle"]
  ask turtles[set size 4]
  ask turtles[set color white]
  ask turtles[set heading random-float 360]
end 

to go
  ask turtles [forward 1]
  wait 0.5
  ask turtles [if pcolor = pink [die]]
  ask turtles [if pcolor = blue [forward 5]]
  ask turtles [if pcolor = red [set shape "cow"]]
  ask turtles [if pcolor = yellow [wait 0.001]]
  ask turtles [pen-down]
  if not any? turtles [stop]
  ask turtles with [pcolor = black]
  
  [if random 100 <= 5 
[hatch 1 
[set shape "turtle" set size 2 
setxy random-xcor random-ycor 
show "Turtle born!"]]]
  
  if random 100 <= 5 
[ask n-of 2 patches with [pcolor = blue] 
[sprout 1 
[set shape "cow" set size 2 
set heading random 360 
show "Cow born!"]]]
end