I don´t care, someone else did the Necro, so i just roll with it.
Halo 1 was "innovative"?
If so, here are my impressions on why it could be called that:
Story: While some might think "heres Aliens, they are bad, go kill them mofos" is the main plot, that is wrong.
Halo 1 set of a completely artistic turn by starting in the middle of something, they find a giant ring in space you know nothing about, the main character YOU PLAY is UNDEFINED as a whole, all you know is that he has been on cryo for some time, you don´t even get to see his face, EVER.
At the start, you have no guns, nothing, still you partake as the ship gets run over by some alien race(s) you´ve never seen before and don´t know what the hell they want from you. That´s done in HL1 too, but not to the degree since YOU actually caused it.
Then you mow down the attackers, land on the Ring and are pretty much stranded.
Also, Halo 1 seemed to be introducing tactical combat, where YOU could see and sneak up to enemies without them knowing, and even take them out from long range without them noticing, thus, breaking their defences without a fight.
Then there was the vehicles...i was amazed how much fun it is to run over some perky critters in a military jeep until Forehammer brought me this nice piece of equipment.
You Unfold the History and meaning of the Ring (the latter in a nice plottwist) as you progress, still you have the feeling you want to leave this god forsaken ring, specially the moment the Flood zergrush you.
AI: while not the best in gaming history, taking out the elite and seeing the grunts run in fear screaming "Elites down, get the hell out!" and here the Marines gratulate me on a nice kill was kind of aspiring to always kill them first, because they seemed to be in charge.
Believability: Even in it´s Sci-Fi setting, everything seemed to be build on with logic in mind. The Hangar scene in the beginning of the level with Keyes and Cortana narrating like we knew what happened (which we didn´t, only they where there) was also a nice touch. This is also a nice touch to Halos believabilty, you don´t get briefed.
You don´t listen to some Mentor type about what happened and why you are here, because THEY don´t know themselfs.
All that is important is the Cole Protocol, you don´t know what it is. All you know is it has to do with the Aliens not finding the Earth by saving the AI at all cost, and so you go.
Also, the Marines seem like a combat force that have seen some stuff in their past, not like in previous games where you either have been alone, or surrounded by incompetent fucks whom the situation was too much a burden<.<
Weapon limitation:
A Super duper 1000lbs heavy super soldier can only lift 2 weapons, while a doctor from Black Mesa can carry a pistol, a revolver, a crossbow, a rocketlauncher, an SMG/assaultrifle with a Grenadelauncher, a shotgun, some grenades and Ammo...?
Wow<.<
Vehicles: FLYING BANSHEES WAS AWESOME!
Well, there is probably more too it, but i also like the grafics.
Thats all on my part.