1. Eternal Darkness: Sanity's Requiem, Gamecube.
A fantastic game spanning various historical moments that is obviously influenced by writers such as Edgar Allan Poe and H.P. Lovecraft. Not only does it do the sanity mechanism well, but you can really tell they've done their homework with all the different historical chapters. Fun fact: It's the only Gamecube game that I like that I own, and I bought the Gamecube for about £50 specifically to try Eternal Darkness. I don't regret a thing about spending about £60 just for one game.
2. Silent Hill 2.
A horror game really not for those easily scared. You play as James Sunderland who must look for his wife. However, creatures roam about, Pyramid Head is relentlessly chasing you and you find other survivors who don't quite add up. The strangest being Maria, a woman who resembles your wife, but is the complete opposite. In terms of symbolism and depth, Silent Hill 2 is the best about, with a story that answers just enough to leave you content but leaves enough lose ends to let you think on it later on. You can really see why later Silent Hill games borrowed the concept of symbolism and self-punishment from Silent Hill 2.
3. Rune: Viking Warlord.
Possibly one of the least known titles on the list. It's a game that gets the idea of Norse mythology and runs with it all the way. Everything about the game screams Viking and makes you feel like a bad-arse while you're at it. The environments range wildly from under-the-sea, to Hel, to mountains, to cities and more. You gather up weapons bit by bit which gives you a nice feeling of actual progression, each weapon looking noticeably different. In terms of Norse mythology games, this game flies above the rest.
4. Kane And Lynch: Dead Men.
This is the most controversial title out of the lot and a lot I like contradicts what most people criticise it for. The story was thrilling and exciting, with various environments. The characters felt real and raw, their anger usually coming off as appropriate, especially Kane's anger. The story plays out as a tragedy as simply everything goes wrong and ends with a downer ending that doesn't come off as shooting the shaggy dog. The multi-player is where it shines though, with fragile alliance having the single best exclusive multi-player mode I know of. A game mode that plays upon greed, something that goes down to human nature and psychology than out-right skill. Each mission varied, with some feeling like global-theft and some feeling like a bank job from a classic crime film. It really is a game that ended up being better, at least personally, than the reviews chalked it up to be (obviously excluded paid reviewers, shame on them and Ubisoft).
5. Mount & Blade: Warband.
This is one of those games that puts realism above anything else. However, unlike most other realistic non-RTS games, it isn't a FPS. Rather, it's a third-person RPG based in the medieval age. The extent of realism is fantastic with the need to feed your men, equip yourself and charge into battle. What weapon you use also makes a difference, with maces being able to knock people out and doing better against people with things like plate-armour, while swords are good against people with lighter armour and usually doing more damage across the board. If you are a female, people laugh you off as though you have nothing useful to say and you never will, an act of sexism realistic for it's time and always interesting. You can make money in various ways including trade, competitions and bandit raiding. You can create your own kingdom or help another kingdom succeed (either someone who has come to you after being kicked out of their own kingdom, or one of the kingdoms already in place). The amount of detail in the game is fantastic and how good it is at what it sets out to do is surprising considering the size of the development team. This is by no means a big-budget game, but what you get is a fantastic game which is easily modifiable and has multi-player.
6. Killing Floor.
While not as small budgeted as Mount & Blade: Warband, it's still not a big budget title by any means. However, the amount of work put into the game shows. You play as one of the many character skins and as one of about six classes (sharpshooter, berserker, commando, demolitions, support specialist and medic) as you have to fight with wave after wave of creatures. The creatures vary wildly from the zombie-like Clot, to the insanely powerful rage-powered Fleshpound, to the gun-wielding Husk. Meanwhile, your characters are spouting cockney lines that are humorous and cheesy, without being too silly and often to get annoying. It's a game with a lot of personality to it. Each of the six classes has a levelling up system and vary wildly in what perks they have that gives you an incentive to use a class you're weak as. It can also be adrenaline inducing as the rest of your team mates die and you have to kill over 100 creatures with whatever weapons you can find (since it's clear you're not going to have enough ammo).
7. Demon's Souls.
Admittedly, this is when things got a bit difficult, trying to think of games I have played time and time again out of absolute enjoyment. Demon's Souls, while it has a bland setting that reeks in genericness, it has a solid RPG feel. While you can't make a character that you'd ever want to touch, all the mechanisms in place is fantastic to toy with. The game-play is very enjoyable and one of the game's shining points as it's unforgivable for errors made. Another shining moment is the environments, making sense and yet varying. Each one, you can really tell have a back-story from a prison where deviants, assassins and other criminals would generally rot away after being tortured, to a mining valley where men were forced to mine by guards employed by the king, their forms shifting to reflect the toil inflicted on them.
8. Heavy Rain.
Straight off the bat, I will admit this: This is the most beautiful game I have ever played. Not just the graphics, but also the music and the general atmosphere. While the story wasn't fantastic, it felt pretty strong and I'll admit I didn't see coming who the killer was. The character writing is pretty good and strong. It falls hard due to the general control scheme being a bit on the weird side and the heavy reliance of "press X to not die", but as a cinematic game, it did it's job and it did it well.
9. Deus Ex: Human Revolution.
By far, the newest game on the list. Well, where to begin? The graphics are nice. The environments are fresh and inventive. The story is strong, questioning vital things that can be taken away from the story and applied to modern day society. The main characters are interesting, even if the minor ones usually come off as shallow and 2D. The game-play is pretty much solid with augmentations that are fun, but sometimes are over-powered and borderline vital for some bosses with no warning before hand. While you can't go through the world with whatever build you want and succeed, it's as close as it gets within this decade.
10. Dragon Age: Origins.
This is fantastically executed game with a fantastic array of characters, a solid combat mechanic and a good story that was bleak enough to be interesting. Sure, they could of gone full-out fantasy, but sliding some dark material really helped formed the world and make it seem more real than pure fantasy. My first time starting off as a city elf was spent half in surprise and half grinning at the interesting racism at hand. Yes, it was symbolism for the racism black people had to suffer, but it felt fresh and new. The only thing that really made the game suffer was faulty coding concerning expansion packs and EA's poor customer service that ended up not fixing the game. It still sits in Steam a broken wreck.
Special mention: Lord Of The Rings: Online.
While, as a MMORPG, it's decent, considering it's free-to-play system it's absolutely fantastic. It's free-to-play, but you can buy non-combat extras using coins that you can either buy or earn in game. However, they go beyond just simple cosmetic extras and onto things like professions, character slots and money limits. As a game, it's enjoyable, even if the Elves and Dwarf origin stories tend to be annoyingly dull. However, Hobbits tend to have a wonderful starting area full of life and back-story to them. The graphics are not really not-worthy and the combat systems for each class have interesting mechanics. As a free-to-play MMORPG, it's definitely worth trying.