Golly

Golly is an open source, cross-platform application for exploring cellular automata. Features include bounded and unbounded universes, fast generating algorithms, Perl or Python scripting, and a state-of-the-art pattern collection. Other features can download patterns, rules, and scripts from online archives, includes a state-of-the-art pattern collection, can paste in patterns from the clipboard, unlimited undo or redo, configurable keyboard shortcuts, auto fit option keeps patterns sized to the window, full screen option (no menu/status/tool/scroll bars), supports multiple layers including cloned layers, many different types of CA are included: John von Neumanns 29-state CA, Wolframs 1D rules, WireWorld, Generations, Langtons Loops, and Patersons Worms, the RuleTable and RuleTree algorithms let you plug in new rules, responsive even while generating or garbage collecting, reads RLE, macrocell, Life 1.05/1.06, dblife, and MCell files, and can also read common graphic formats: BMP, PNG, GIF, and TIFF.

Whats new in this version:

Version 2.5 has added a new rule format.