Everything halo did was done before, i'm sure vechiles existed in other FPS's before halo, and battlefield 1942 did vehicles way better. Perfect Dark had co-op. Acctually come to think of it, perfect dark was LEGUES ahead of halo, and it was older. Half-life and counter strike despite being older, were also much better FPS's then halo.
I'll give halo one thing it pioneered in: It dumbed down FPS's even further to make them more accesible to the masses. That is why it's so popular. With all mass appeal comes simplicity. Halo did introduce recharable health. Thats really damn simple. Anyone can learn to just lie low and get health back. Is it balanced, not really. Also i find that Halo has a humoungous health bar, it takes 2 full clips from the SMG (dual wielding) to kill someone, and that is massive. 3rd person vehicle mode that gives you greater periferal vision, awesome. Super slow movement, so no one can get away or hide for cover in a fire fight, awesome. A melee botton so you don't have to change weapons to say a knife, so that way if you miss your melee attack you can keep on shooting, or if you run out of bullets, just melee for the kill, all of this with no concequences because you don't need to account for your ammo in your clip, or worry about weapon change, exellent. Auto-lock and forget anti-vehcile rocket, that fly through walls sometimes to hit their target, that is also great against infantry cause the splash dmg is so HUGE you just jump and shoot the ground, spectacular. Floaty jumps like we're kirby, cool. Halo 1 was also notorious for gernade spam(massive splash + insta-kill=lame), and an overpowered pistol (which is acctually do to the run speed not ther pistol itself, but thats how i feel, and most casual players didn't know this so i'll ignore it) but i won't go into those. Tracers on sniper rifles, cool, so we can find those bad boy snipers. How many games require tracers on any of their sniper rifles? I can't think of any, but it sure does make the game simpler.
Halo = even simpler fps then normal standards. And it surprises me that no one has been able to copy their succsess. If not copy it, just clone it shamefully, theres a truckload of money to be made by this casual type of FPS.
Rainbow six, i don't know if it created the whole squad based FPS, i'm unsure, but if it did then maybe it could count as revolutionary. Deus ex i have never played, nor do i know anyone who has, so i really can't credit it to anything, when did it come out and what did it do different? And i think DOOM came before wolfenstien, i gotta check that out.
Edit: Yup, your right, wolfenstien came out 1 year ahead. So i'd replace doom with wolfenstien on that list.