Sure, you can get the "game" here:
http://gavos.free.fr/volatil/petri.zipWe have not managed to make it interesting yet (still need some time). The goal is to cover the biggest surface on the screen. Right-click to create a "stain" anywhere, left-click to create on your on color.
The garbage collector is enabled by default. Just create a few stains in a row and you will notice the small freeze, like the stains pausing their progression and then resuming (it happens at last least once a second, actually). I forgot to say that I am running on Windows, maybe the GC perfoms a very different way on this platform?
The code responsible for the graphics part is in window.rb, and here are a few keystrokes we created for testing:
'E' -> enable garbage collector
'D' -> disable garbage collector
'C' -> clear the screen
'Esc' -> quit the game
'O' -> select round stain
'X' -> select cross shaped stain
'R' -> select red color
'B' -> select blue color