I'm still going to say it brought a feel that hadn't been seen before - except in maybe the Half-Life series.
Yeah other games had vehicles, but they weren't anything like the ones in Halo. I also forgot one thing that made Halo something special. --- Cooperative play.
Other games may have had some of the aspects of Halo's multiplayer, but they did not offer the cooperative play that got so many, many people hooked. Not only were things like the vehicles different than in Battlefield and UT, in that they drove VERY uniquely and could do awesome things without falling over, getting "stuck", and in some cases blown up, but you could play through the whole game with someone else. Working together to bash the crap out of aliens, sticking plasma grenades to one in a group and watching your partner run for cover like an idiot. It was good stuff, and no other console game offered such a thrilling experience.
The multiplayer sucked, had always sucked. It was somewhat improved on the PC because of having lots more players, and the modded servers can be fun with just the vehicles and rocket launchers, but as a whole I agree nothing new.
As a whole I'd say it was the "movie" feeling the singleplayer game had, the ability to play through it co-op, graphics - which for it's time were damn good and kept a lot of people "wow"ed, and the unique nature of the vehicles (more so what you can do with them with how they'd drive and interact than the vehicle designs or operations themselves). That sort of thing had not been seen on a console before.
It didn't revolutionize anything.
Just made for a fun, unique console game.
Keep in mind Thor, we're talking about the XBox. An absolutely horrible console that didn't have any good FPS games at the time.
