Haven't played any of those, so anything counts! Thanks in advance!

It should be pretty obvious, but the first Call of Duty is sort of an unmissable landmark in the genre because of the way it handled storytelling at its time.

And Call of Duty 4 was sort of a historical tipping point, at which the series was promising to get seven kinds of revolutionary (instead it became the blandest crap in the world, but what can you do); and it's also a very good example of great, adrenaline-pumping narrative with some fantastic set pieces, including at least one genre-defining moment you're guaranteed to remember for ages. Hell, even Yahtzee liked it at the time, which should tell you something.

The whole Call of Duty series is decent, not more, not less. I liked the first PC Medal of Honor much better when I played it recently. Overall I can recommend all three PC games in series, but the second tends to drag at times and the third is very short.

I recommend Crysis, it is a great mix between linear progression between big, open levels; at least during the first half. It also has a war theme going on (Koreans against US, later aliens against all). I also liked the open levels of Chrome, but the difficulty is a bit off and it is not really war-themed (background is a corporation war).

He's asking for war-themed games, so I doubt Crysis fits strictly there. For one thing, the protagonist is a super enhanced blah blah blah uber techno armor blah blah blah FROM THE FUTURE! LAZORZ! SUPER POWERS! PEW PEW PEW!

And then you have Crytek's stubborn trademark of ruining everything by throwing in some retarded sci-fi enemy in the mix --in this case, aliens complete with spaceships.

The fact that there is a war going on is mostly cosmetic.

The first Medal of Honors really deserve the attention (Allied Assault and expansions, Pacific Assault). In terms of combat realism, Call of Duty was closer, although aggressively cinematic even at that time. But in terms of atmosphere and gameplay quality, MoH is the best there is regarding war-themed FPSs.

Another popular WWII series is Brothers in Arms, but compared to the ones already mentioned, it's focused on tactics and the FPS mechanics are deliberately inaccurate. The tactical warfare does not surpass the quality seen in third-person tactical shooters Conflict: Desert Storm and Full Spectrum Warrior, so BiA games are really strange beasts.

Another very good war-themed FPS is Vietcong. The jungle warfare feels better than in Far Cry or Chrome. Coupled with the fact that it's one of the few FPSs exploring the Vietnam conflict, I think you should really play this.

I'll finish this post with a weird entry. Bet on Soldier games are technically war-themed since they're placed in a conflict raging around the world for over 80 years (!). The catch is that people are so bored of this war, that they organise competitions to the death between soldiers. These fights take place in the war itself, so technically you still have to accomplish different missions, before challenging the other contenders. In the end it's not as polished as the traditional FPS series I've mentioned above, but it's pretty interesting to pick up and play.

Best recommendation of the thread; game's oozing with atmosphere, which extends to its two add-ons. Vietcong 2 is also worth a playthrough for the very same reasons (urban combat in Hue, etc.), but ultimately falls short of the original.

Operation Flashpoint

ArmA 2

Have "fun"!

These.

Probably wrong to call them shooters, but as far as an actual 'war' theme goes, instead of 'superhuman soldier suddenly wins the war single-handedly' as most FPS like to do (out of those mentioned I think Brothers in Arms is one of the few exceptions), there's nothing better. I deeply despise anything and everything military, but these are still among my favourite games ever.

Edit: Just steer clear of the post-2002 "Operation Flashpoint" games. Although maybe they're okay as traditional war-themed shooters, but I played the first and didn't like it at all.

Medal of Honor: Allied Assault, Call of Duty and Call of Duty 4 are probably the hallmark entries that should definitely be given a try. I really liked MoH:AA and CoD. I think Call of Duty 4 deserves more credits for its multiplayer than its singleplayer component though. There's a couple nice missions, but most of it is all cinema no gameplay. If you've seen movies like Black Hawk Down the American missions will give you nothing new. If you enjoy these games it might be worth to play the other games in the series as well, but if you just want to pick up the top players I'd start with these.

If you want to go a little more tactical I can also heartily recommend Hidden & Dangerous 2.

Would definitely second Vedders Allied Assault and CoD4 recommendations. Whilst Vedder does have a point about CoD4's American missions, the SAS mission narrative does a pretty good job of making up for it. As for AA, there's little to complain about, ending aside.

I really like the original two PSX MoH, but if you're mad about an FPS played with thumbsticks I can't imagine how mad you'd be at an FPS played with a d-pad and shoulder buttons. I can't remember anything memorable about AA, but RS was stupid James Bond bullshit (they were almost going for 1940s era propaganda movie, but then went way overboard). I really liked how EA was more open ended and had optional objectives, but a lot of people hated it, and it is very short.

As for CoD the first is still a really great game, and CoD4 is the successor to that in every way. MW2 is great too, even if it felt like it was holding back (then again, considering what civilians in warzones looked like in Homefront, maybe IW was right in keeping them out of MW2). Every other CoD is either terrible, or only good for its MP.

One more vote for Medal of Honor: Allied Assault. I recently played Delta Force too, had fun with it.

While everybody is recommending Medal of Honor: Allied Assault to hell and back, I'd give my vote to the first two PSX Medal of Honor games. Yes, if you are displeased by playing a first person shooter on a console (especially of an age where shooters on consoles were far from a norm) it might not be the best recommendation, but I think the relative uniqueness of the two titles and even the technical limitations of the console made for very interesting level design and overall atmosphere (stuff like the mission "Where Beagles Dare"). The lack of save function in-mission can be seen very detrimental in light of modern age, though.

Come to think of it, you could always play this on ePSXe for the resolution boost and save states. You could also pretend it's a pre-mouse look game with manual aiming hacked in. I didn't make much of a case for it, but I did really like MoH 1/U's use of adventure elements. At times they feel like a downgraded Perfect Dark or NOLF. They're also nice to see developers attempting to make set pieces and running up the the absolute limits of what was possible on the hardware.

Seconded. The ps1 MoH games are pretty much the only military FPS games I've bothered seeing through to the end. Normally the thought alone of a game in this genre makes me walk the other way, but these were quite entertaining and really pushed the ps1. :)

Something should be said here about the Battlefield series. There's not much to go on if you're looking for single-player campaigns (even the most recent Battlefield campaign mode was pretty light and unremarkable), but if you can stomach online competition, grab any one of them, they're all good fun.

Yeah I left those out because I don't believe Oleg plays multiplayer games. The old ones didn't have single player and the new ones do, but it's pretty bad imho. Battlefield 3 with at least 3 friends online is freakin' awesome however.