Our list of the 39 best ever first-person shooter games continues with SWAT 4 and Spec Ops: the Line. If you don't agree with any of our choices, let us know in the comments field below.
11. SWAT 4
Why it's great: A forgotten gem from the creators of Bioshock, this is rare proof that military shooters don't need to be po-faced, thick as two short planks and all about who's got the best gun. Ideally played in co-op, SWAT 4 sees you and a squad of all-too-fragile chums trying to take out the bad guys with a minimum of fuss - sometimes even non-fatally, with the use of a gun that fires high-velocity bean bags. Whether bloody or bloodless, every mission requires extreme caution, communication and forward planning. Add to that couple of remarkably creepy levels and you've got something that's quietly very, very special and one of the best co-op games of all time.
12. Spec Ops: the Line
Why it's great: The tedious name belies what's proven to be one of 2012's biggest talking points in gaming. Sure, it's a fairly ordinary third-person shooter in terms of action, but it's got two aces up its otherwise forgettable sleeve. One is the setting, a post-disaster Dubai that pairs gleaming skyscrapers with sandstorms. Luxury yachts litter the dunes, huge billboards promise absurd indulgences amdist the burned bodies... It's a darkly memorable sight. On top of that, the game poses difficult questions about what it is to be a shooter, and what the consequences of such extreme violence might be. Which rather makes it a shame it's so guilty of what's it's criticising. Whether you agree with its message or not, it's something of must-play. See also: Spec Ops: The Line review.
13. Team Fortress 2
Why it's great: Ah, the great multiplayer leveller. While this cartoon-esque team shooter does have plenty of room for shooting expertise for those who desire it, it's also an instant-fun riot for rank amateurs. Pick the character that most appeals to you - the slow but steady, blood-crazed heavy, the headshotting Sniper, the fast-running scout, the rocket-jumping Soldier - and get in there. You don't have to be good at shooters to feel like you've contributed, and you're guaranteed a laugh. And if fighting other players seems a bit too scary, TF2's recently had a co-op mode added in which you and four others fight off hordes of AI-controlled robots. A true classic.
14. Metro 2033
Why it's great: If you like the sound of S.T.A.L.K.E.R. but think it sounds a bit too free-form and maudlin for you, cast your eye Metro 2033's way. It's got a lot of its fellow Ukranian game's vibe, but opts for more of a rollercoaster action take on irradiated mutants and post-apocalypse survivors. Not that it skimps on weirdness, mind - Call of Duty this most certainly is not. Given Metro 2033 is packed full of memorable sights, both in terms of monsters and showing the starving society hiding from the horrors on the surface inside Moscow's subway system, it scarcely matters that its shooting feels a little off.
15. Dead Island
Why it's great: Well, it's not for everyone -hardly bug-free and more than a little obnoxious in tone, this tale of a zombie outbreak on a Caribbean island is very much an acquired taste. Stick with it and it's full of surprises and a palpable sense of danger, while the juxtaposition of groaning dead-head and blissful beach setting never quite loses its edge. Like so many of the more timeless shooters, sense of place is just as, if not more than, important than how satisfying it feels to unload a full clip into something's face. And here, the weapons you use are cobbled together from what's lying around in this former paradise, rather than waiting in convenient ammo crates. There are admittedly many things Dead Island fumbles, but giving its players a overwhelming sense of desperation is not one of them.
16. Far Cry
Why it's great: Speaking of paradise islands, here's a game today's on-rails shooters could do with learning a trick or two from. Far Cry was the predecessor to Crysis, but for much of its duration it avoids sci-fi in favour of having you battle armies of mercenaries across wide-open outdoor spaces. There are speedboats, there are jeeps, there are even hang-gliders. Far Cry's best levels have an incredible sense of scale, and with it great freedom to approach battles in the way you see fit. Sadly, its indoor-set levels, and the eventual arrival of frankly annoying simian mutants, sees the second half of the game lose its edge, but it can't undo the huge, emergent achievements of the first half.
17. Dead Space
Why it's great: From afar, Dead Space looks like it's guilty of every sin in the shooter design book - oh so much brown, cramped metal corridors and a lead character who's entire personality is in his silly outfit. But this slow-burn horror-shooter knows what it's doing. It's all about feeling more tangibly a part of the creepy, deep space world you're playing - from the crunchy thud of your huge metal boot on either floor or mutant skull, to the use of a mining laser as a weapon which gradually carves away at enemies rather than just make them fall over, to the way the game's interface - health and ammo counters - are shown as lights along your character's spine rather than bars at the bottom of the screen. Plus, an overwhelming sense that everything really is going to hell and there might just be nothing you can do about it.
18. Quake III: Arena/ Quake Live
Why it's great: Perhaps *the* definitive multiplayer shooter for those who want a no-nonsense test of skill, Quake III's intense battle of shotguns, rocket launchers and railguns was recently reborn as the free-to-play, browser-based Quake Live. It's as rewarding and as brutal as it was a decade and a half ago, although the payment models (for access to additional maps and modes) haven't gone down too well with everyone. There's certainly something eternal about Quake III - a perfect blend of speed and accuracy, and the constant, sport-like striving to forever better your own abilities.
Why it's great: Back in the early 90s, the gaming industry hadn't yet decided that shooters must necessarily be about a man with a gun running down a series of corridors. Descent has you playing in small spaceship, in a zero-gravity environment where you have freedom of movement in all directions. Unlike the vast majority of shooters since, you're able to approach the level from any angle you see fit, which as well as being hugely liberating means fights are arguably more about tactical movement than aiming aptitude . Descent compensates for your extreme mobility with extreme cruelty, never afraid to dump overwhelming odds on you with no notice. If you can't quite stomach the appearance, look instead to 1999's 3D-accelerated Descent 3.
20. Tribes: Ascend
Why it's great: 'free to play' is as terrifying a phrase for life-long gamers as it is exciting for the men in suits who secretly rule videogames, as it's been horribly abused in a very short space of time. Here's a game that really gets it right, however. This 2012 reboot/remake of the peerless jetpack-based online shooter Tribes, it retains the heart and soul of the game while adding in plenty of new stuff and a much more modern look. It's also very good at offering the choice between paying for or slowly earning via play its assorted new weapons and load-outs, so it doesn't seem to exist primarily to ask you for money. However you choose to lay hands on new goodies, the thrill of Tribes is that success relies on so much more than being able to move a cursor around rapidly - you've got to understand the 3D space you're in, and the tactical opportunities having a jetpack strapped to your back affords you.