Ok that makes one. Any more that I would miss out on if I use one button?
4-way games that use 2 buttons:
Dig Dug II
Satan's Hollow
Son of Phoenix (technically 8-way but works fine)
Super Cobra
Honorable mention:
Punchout looks great on a vertical cab (puts both monitors on the vertical screen). 3 button game. (Left hook, Right hook, Uppercut). On my cab I on have 2 buttons so I map uppercut (button 3) to the player 2 button.
Also, are you going to run any horizontal 4-way classics on there? I did on my vertical cab. They look pretty decent.
Zookeeper (only uses 1 button but it's a fave of mine).
Elevator Action (jump, fire)
DeL