I was approached by one of the creators of an add-on for Pac-Man arcade machines to write a different menu system for their multigame selection hardware. The hardware allowed for 16 different games to be selected from, and saved high scores. The original menu was a simple list of game titles on a single screen. The user would select the one they wanted with the joystick, and hit start.
My updated menu displayed screenshots of every game, added many more game modes, as well as a few games, including a Z80/Pac version of "QuadBlok", my Tetris clone. I was exercising their hardware so hard that a bug showed up that was not exhibited in the old code. I also added a few other games that ran on similar hardware, which required a lot of disassembly, reverse engineering, and patching of those games.
I borrowed ideas back and forth between this effort and the "MPD MsPac" effort.