1. Doom (1993)
If Wolfenstein was the prototype and Quake is a derivation, Doom is FPS gaming purified. It has so many elements that appeared first in their basic form and with greater depth than games decades later would attempt.
For one, it had such detailed environments and I don't mean cosmetic features, I mean it had meaningful detail in the layout,
And it had variety of enemies beyond the cosmetic, enemies that you knew you had to approach differently and were different threats.
Of particular note is an aspect unique to video games as an art form and that is the moddability. You can't mod a film and modifying books is strangely hardly ever done, but Doom was the first to really get this from its inception with WADS and further with source ports. It's a major factor in what it has kept it alive and relevant today and more than that, even superseded many games in many important aspects. Mods like Brutal Doom have made a visceral game that puts the likes of Gears of War to shame as compromised.
2. Half Life (1998)
This showed how narrative flow can be done in an FPS. Doom used title screens and scrolling text, clearly cutting away they would have used cutscenes either CGI or live acted had they the time, Half Life showed a subtly as significant as the concept of Montage storytelling did for motion pictures(rather than just having a narrator or text-frame give context and exposition).
Counterstrike would have to be included with this. It started as a mod for Half Life and likely would never have existed without being a mod first. Everything after that is iteration.
3. System Shock 2 (1999)
Another game changer, in how to expand on the essentials of FPS gameplay with meaningful choices and variety.
While certainly not without flaws (disintegrating firearms) these were minor incongruities that didn't detract from the tone befitting of a single-player game.
4. Team Fortress 2 (2007)
Not least for the competitive multiplayer but for the approach including completely game-changing modes like Mann vs Machine.
It owes much to it's predecessors, but still none can top it. Of particular note it was its achievement in tone, to resist the temptation of going for ever more "gritty grim dark realism" in what is an inherently ridiculous circumstance which defines online FPS games that was like a Road Runner cartoon in practice it should also be in concept. Though still be a very original overall design, hardly anyone could mistake even a single frame of Team Fortress 2 for being anything else.
The previous mentioned here I praised for their mods which are fundamentally limited with an online game everyone using the same mod, TF2 deserves credit for continual enhancement of an online multiplayer. Such
5. Left 4 Dead 2 (2009)
I see earns its place as trying something that really had never even been done before and not succesfully imitated.
It's a game which above all else depends on teamwork.
There is no other gameplay experience like this, fighting as a group against such incessent waves of attackers.
I am treating Left 4 Dead 2 as "Left 4 Dead 1 Redux" as it now includes all L4D1 maps and modes without compromise.
-Call of Duty 4
such promise but squandered, repeatedly. The idea of RPG elements into online FPS multiplayer were pioneering but the first iteration wasn't so balanced and each subsequent update has erred more towards the gimmicks, refusing to address the fundamental balance issues. The weapons were still either all too similar or overpowered. Pick your own Perks lead to either unbalance or mediocre changes, it couldn't have pair perks with nerfs.
The single player was a fresh experience till the developers showed they couldn't resist the temptation to cross over into the ridiculous... yet make the double mistake of continuing to play it straight. Zombies mode of Treyarch games is the only part that gets the tone to match yet is held back by grinding gameplay that makes killing zombies a chore. I mean every round making them more of bullet sponges?!?! What were they thinking?!?!?
They showed their death of a protagonist for the gimmick it was by its overuse and lost grip on its sense of relate-ability and humanity in amongst the extremeness of the situation. Call of Duty 4 was positively light hearted compared to latter games that piled on the melodrama ineffectually.
-Half life 2
Again, such promise but squandered
To spite being a decade old next year most of its ideas on pacing and variety are ignored and in its place the concept of set-peices and railroaded narrative instead.
Persistent-Perspective storytelling had so much potential, but increased it's been used and abused as a crutch.
This raised the bar, but others didn't follow. Even Valve, except for the Episodes that felt too much like refined retreads. All very good games but it's importance has yet to be fulfilled.
Like for example, why is it 9 years after Alyx Vance effectively crossed the uncanny valley with relatable facial expressions are games still populated by Botox People? Alan Wake was surreal for all the wrong reasons for the supposedly relatable members of the cast looked like an android had ripped off someone's face and tried to use it as a mask.
-Team Fortress Original
While this deserves to be heaped with praise for it's ambition, and no less for so early in FPS history and no credit lost for basic graphics... it was far from refined.
It was brilliant for it's class structure but really it still feels like a brilliant first draft. Team Fortress 2 feels like the fruition of the concept in tone and breadth.
We appreciate thee, but the prize must go to the successor.
Would be on the list but feels like a squandered opportunity after System Shock 2.
While an original environment, it was far too incidental. The Ayn Rand circumstance was little more than a neat backstory and had little to do with the depth of the environment and was such a tease, lacking any kind of fleshing out. In retrospect, it came off as an extended demo for a deeper concept. Lots of ideas not so fleshed out. I mean a society ruled by raw capitalism and self-fulfilment, money wouldn't be such a static and simple thing, bribery and conflicting financial interests should have been paramount.
And it's an underwater city with no swimming sections. The post-crash section showed they could do it. All adding to the environment being an incidental cosmetic part of a what is supposed to be more than a visual medium. The water was Chekhov's gun, and they didn't use it.
Oh and 2007, 3 years after Half Life 2, still has facial animation so deep in the uncanny valley it would have been better off having much more basic graphics.
-Portal, Thief, Elder Scrolls series, etc
For not really being First Person "shooters"
-Mass Effect, Max Payne, Spec Ops: The Line etc
Not really "First Person" shooters
-Serious Sam, etc
While good, they were hardly innovative nor pioneering. Throwbacks cannot push off originals.
-Far Cry 1, 2, 3, Crysis 1, 2, 3
Again, taking sprawling maps concepts but more HD retreads of lower fidelity predecessors.
These owe a lot more to predecessors.
Same problem with Modern Military Shooters, Melodrama without humanity.
Credit to Halo ODST, by far my favourite in the series for it's narrative structure, relatable characters and shift in gameplay focus and a protagonist that isn't in the Master Chief middle ground of being unable to decide if they are a stoic character or a blank slate for the player to embody. It actually feels like you are in a real war playing a few grunts scrapping on the ground, rather than just a super soldier running around from objective to objective, ordered so by people who seem to have a much better overall picture.
Again, I liked Halo. I wanted to love it. But you see why I cannot.
-Innovation in single-player games.
My list is topped with multiplayer games as single-player experience has gone through many graphical upgrades but still the likes of Doom far as well or better than almost all games today. Half Life 2's pioneering concepts are rarely followed up on, even by Valve. Hell, they wrote a book and filled the game with developer notes THEY TOLD EVERYONE HOW TO DO IT!
But the only thing they took was the worst aspect, the railroaded, setpeice constrained linear corridor with virtually no lateral freedom, no choices in which way to go next. Half Life 2 compensated for this, it was imperfect for the lack of any need to think about where to go next so the play had no appreciation for the breadth of the environment they were in.
-Modern Military shooters
I still think developers are caught up in the mythology of "authenticity" of warfare, not realising that real war sucks and trying to make it authentic won't make it something people want to play. They need to come to this realisation and recognise the appropriate tone for such games, and it's not depress-o-melodrama cynicism of Spec Ops The Line. They almost had it with Call of Duty 4. A sense of humanity. A sense of daring heroism. Not just running and clicking.
-Kills focused FPS games.
Like typical Call of Duty multiplayer (as opposed to objective focused TF2). Because these are recipe for disappointment.
The fact is every online game the average kill to death ratio (excluding self-kills) must be 1:1, half the people will have a sub-1 kill/death ratio, you are dragging your entire team down, the game would literally have been better off if you had not joined. But in an objective focused game everyone contributes something and it's not so obvious you didn't make a huge contribution and ultimately kills and deaths don't mean so much.
I think these is a latent market for competitive FPS games that squares this circle. Purely about people running into an arena and shooting each other in a way that doesn't simply exploit less skilled players being cannon fodder for the more skilled, you then have a ponzi scheme that depends on a constant stream of new players who have to depend on being slaughtered till they get good or give up.
This needs to be broken with innovation in gameplay and scoring.
Something where people can be continuously satisfied from beginner skill level to mastery and in all sorts of combinations.
We must have a return of deathmatch. It's quite clear why Team Deathmatch took over yet true teamwork did not, people