Any Z80 programmers out there looking for a pet project?
If so, you could make the world a better place by adding more levels to the arcade version of Mr. Do.
You know how levels 2 through 9 each have a path/tunnel shaped like a number?
What if there were additional levels that had paths shaped like letters (A through Z).
Otherwise, exactly the same game. No additional features -- just more mazes. The existing game logic should do the rest on its own.
Anyway, food for thought for anyone out there looking for something interesting to hack away at. I'd do it myself, but I'm completely ignorant of Z80 machine language programming.