It was pleasant to operate free of the theme and time constraints.
If you have difficulty understanding what to do in the game, some hints:
1) the only time a cell in game world is ever updated is when you walk onto it, and what happens to it is influenced by its four immediate neighbors
2) several things only have an interesting behavior if their four neighbors are "clear"
(If you have any questions or find any bugs, ESC should display a complete transcript of moves you made which would be helpful for my debugging efforts)