I've been trying to find a copy/download of "Load Runner: The Legend Returns", because it's awesome and it had a level editor and stuff.
Did you ever play Lode Runner 2? It was a 3D/isometric version of Lode Runner with a level editor and stuff. My brother was really into it and made some sweet levels.
Anyway, my favorite mac game would have to be Bugdom, because it came with my first mac and it was the first video game I played with any degree of focus. The first level music still makes me want to cry. Unreal Tournament was another favorite as well; it was my first and only FPS (not counting UT2004). I got it for my PC so I could use the editor, which was great because I always fantasized about making my own maps.
Oh yeah. Tropico was great too. I remember faking sick from school so that I could play it all day and eat junk food. Every time I eat a particular kind of cookie (Keebler fudge grahams) I go on a nostalgia trip to me in 8th grade playing Tropico for hours. I want to get Tropico 3, which came out last year I think. It looks really fantastic, and it has improved road-building tools, which is really a fetish of mine. I would probably play a traffic-simulation/planning game if one was released.