The old 1973 Atari maze game Gotcha (their fourth arcade game) has been emulated in DICE, the Discrete Integrated Circuit Emulator. Apparently I missed the boat on this as the emulator was released over a year ago at http://sourceforge.net/projects/dice/
Dice is a very cool "emulator". I was experimenting with circuit level simulation of arcade games when I ran across Dice. I really didn't think circuit level simulation would be fast enough to produce a playable game, but Dice proved that it could be done. I actually added the Gotcha driver to Dice. I would like to try adding some more games but it's a very tedious process.