I almost forgot about the project's original objective that I had in mind when it started one and a half year ago: to build a circuit from TTL components that can play Tic-Tac-Toe on an LED matrix. So lets correct that: today, with minor adjustments, Tom Pittman's Tic-Tac-Toe from 1977 is running on the Gigatron :-) Source code in GitHub.

Ok, the planned LED matrix has morphed into a video screen along the way. That's just feature creep.