Lode Runner
Ghost Recon Desert Siege, then Call of Duty, any of them.
[*]Diablo II
Jedi knight Outcast.. My favorite game when i was growing up. I kicked A.$$
So so many.
I probably logged the most hours on the Escape Velocity series. I still play that now some times.
One of the first games I ever played was an old hypercard based game from 1988 called "The Manhole", which I played when I was little on a macintosh plus, black and white. It was a really cool exploration game, not unlike Myst. Before we got our external 20 mb hard drive, I remember from time to time it would prompt me to change the floppy disk, cuz I didn't have space to install it.
You can include non-Mac exclusive games if you like, but what you would be saying is this: "This is the best game ever made for Mac, but there's absolutely no point playing it because the PC/Amiga/etc version is WAY BETTER"This is a Mac forum, people are discussing the best game they played on their Macs presumably while running the MacOS. The only limit that makes sense to me is excluding those PC games played in Windows on your Mac. Everything else should be fair game even if you think they play better on a PC, it's irrelevant to a best 'Mac' game discussion.
The correct answer is Deus Ex.
But I'm a lenient grader, so you get half credit for Marathon.