Zeraan: Any of the 16-bit games developed for Windows 3.X (you'd need to emulate Windows 3.X to run those) including but not limited to:
Mission: Thunderbolt
Lode Runner: The Legend Returns
Pipe Dream
Old Mac games that was never ported to PC including but not limited to:
Asterax
Maelstrom
Mission: Firestorm (Sequel to Mission: Thunderbolt)
Bolo
Diamonds (and "More Diamonds") -
http://takegame.com/arcade/htm/diamonds.htm, so disregard this one
There are many old games lost to bit-rot :(
Lode Runner The Legend Returns had a DOS version so they could(if they could obtain it) just use that