The simulation runs automatically, in the lower box you can change the rule set for the automata. The max value is 4294967296. As soon as the rule is changed the simulation restarts. Pressing 's' after clinking on the canvas takes a screenshot of the current frame. Some nice behaviours: 123456780, 12345670, 1234505, 12345054, 123450543, 76564534, 4294967286, 42949673, 2911147291 (around this one plenty of funny stuff), 123450542, 12345674.