Oh god don't let the OG Mac fags hear you say that, holy fucking shit. It was a Doom clone with text terminals and jumping. Admittedly a perfectly adequate and quite enjoyable one, but to hear the average Mac fag tell it, it was the single most innovative gaming product ever created by mankind and proof that only the blessed Macintosh was Good Enough™ to be graced by its presence.
It doesn't actually have jumping, you sort of just float from platform to platform. Marathon had floaty Halo movement before Halo did.
Marathon did, however innovate* Dual Wielding in FPS games.
(*the shareware version of Rise of the Triad released the same day as Marathon, and also had Dual Wielding).
I'm not a Mac fag, so I never played the original Marathon Trilogy in the 90's but I would definitely recommend them today if you're into the 90's style Boomer Shooter type of FPS game. Marathon 2 in particular is IMO up there with Blood as the absolute peak of the genre, and they're all free on Steam so there's nothing to lose.
If you're big into stories in games, you can get enjoyment out of the classic Marathon games too, it can be really fun to try to piece together what the fuck is actually happening, and pierce through the layers of conspiracy in the story. Durandal is great too, he's probably best example of the "Insane AI" character archetype, even better than System Shock's Shodan. I wish Greg Kirkpatrick had become a novelist or something after Double Aught folded, he was genuinely a great writer, albeit a little pretentious.
I don't even know why I'm rambling about the old Marathon games in the new Marathon thread, I guess I'm just pissed off at the damage Bungie has done to their own IP by releasing this slop. The classic Marathon games are little known classics because Mac gaming has always been a meme, and if this new game was actually competently made and actually had mass appeal, there could have been a resurgence of interest in them.
Anyways, fuck Nu-Bungie, the company died after Halo: Reach, and they're just a shambling corpse now.