All things Metroid except Other M, because I hear it blows massive chunks. Beyond that, of course, it can't be my favorite if I haven't played it.

Dead Space 1 and 2; not because they're necessarily good games -- which, I mean, they are, but not great -- but because they're some of the most ♥♥♥♥ ♥♥♥♥ I've seen in a game and I love it.

Borderlands; again, not because it's a good game, but because I love the variety of guns, and the constant drive to find new treasure. Especially when it's treasure with which you can blow off a man's face.

Deus Ex because I love sci-fi and moral conundra. Also the fact that the gameplay provides the player with so many options and so much customization. And with Human Revolution, ♥♥♥♥ retractable robot arm blades.

Killing Floor. I play it with my dad and a couple of my closest friends a lot, and it's just a great way to spend time with some of my favorite people. Or, you know, we've made it to be so.

Basically anything Valve makes. Half-Life, Portal, Left4Dead, and their respective sequels are some of my favorites. I have some really fond memories of playing L4D with my ex-girlfriend.

Shadow of the Colossus: I remember when I first saw the 'flying serpent'. I thought "It's beautiful... and now I have to kill it."

CaveStory: So many great moments in this one. If you haven't played it, go do so now.

Psyconauts: Utterly hilarious and occasionally touching.

Achron: A lot more recently released than the others listed. I actually love this one for it's multiplayer mode. An RTS with true, free form time travel. Also has alien cyborg squid with three genders.

Awesome games:
Fallout 1 & 2: Really?
Black and White 1: The second one SUCKED also no Mp in that one.
Arcanum: Like Fallout but steampunk.
Knights of the old Republic 1 & 2: Like the best game in the history of awesome. UOP needed.
Men of War: with the mappack from faces of war.
Fable 1 & 2: Great games, not like the 3rd.
Dwarf Fortress: Modding goblin civ since 2009.

Honorary mentions:
Postal 2: It have't aged with grace though...
Cortex Command: ... well.
Mass Effect 1-3: I like them, not something I'd play through twice though.
Civilization 1-5 second is the best followed by tree.
Super Bomberman SNES: <3
Jade Empire: Very good RPG not many have played it seems, set in japan (it's only flaw)

... And any game with flamethrowers to some extent.

How did I forget this.

Metal Gear Solid 1-4: If this needs an explanation, I'll assume you've been living under a rock
Kingdom Hearts I & II: Two of the funnest ARPGs I've played, surprisingly gripping despite looking like kids' games
Ratchet & Clank 1-3: Three of the best platformers I've had the pleasure of playing
Jak & Daxter 1-3: See above
Final Fantasy X: Great visuals (especially cutscenes), a long story, plenty of side ♥♥♥♥ to do
Dark Cloud 2: Steampunkish cartoonish ARPG with a few unique twists
Ace Combat 4 & 5: Pewpew whoosh whoosh planes nyaaa
Shadow of the Colossus: Giant monsters and ♥♥♥♥ aw yer
Sly Cooper: Raccoon thief all up in this ♥♥♥♥♥
God of War I-III: BLOOD, BLOOD EVERYWHERE
Uncharted 1-3: It's like a modern version of Indiana Jones on cocaine, but even that's an underwhelming comparison
Mercenaries: Blow up ALL of North Korea!
GTA III/VC/SA/IV: Thug lyfe
Call of Duty 4 Modern Warfare: A classic and the height of the now shovelware series
Battlefield 3: Probably the best multiplayer manshooter around
Killzone 2-3: Great fun and "feel" to these two, fluid and stunning graphically
Bioshock: Would you kindly?
Minecraft: Well ♥♥♥♥ where'd 200 hours of my life go
Dragon Nest: Has its share of issues, but great at making you feel like a badass (really the only MMO I know of that does)
Star Wars Battlefront I & II: Too much swag
Battlefield 2: Modern Combat: This expansion/port added an actual campaign (GASP!) During gameplay you can switch control between any live soldier on the battlefield, much like Cortex Command
KOTOR 1 & 2: I AM A JEDI
Red Dead Redemption: Nothing like riding a donkey into combat, killing a bunch of people in slow motion, and hog-tying a hooker to train tracks
Just Cause 2: Story? What story? I'm too busy blowing the ♥♥♥♥ out of everything
Prototype: See above
inFamous 1 & 2: Easily the best superhero games I've ever played, good combat, movement, and story, great at making you actually care about the characters and your actions

Yes those are all my favorites and not just games I like ♥♥♥♥ you

I've probably forgotten a few, actually.

Dude, Sith all the way. But yes. KOTOR all the way.

Haaa, yes. That and driving stupidly expensive cars off of cliffs.

wait how could I have forgotten Dwarf Fortress
and yes everything valve makes, pretty much

You're like the only other person I know who's played that game. Such a good time.

Dark Cloud 1 & 2 were really great games. Wish I still had my PS2 so I could replay them.

Yes, how could you, I guess you are just bad men...

But so am I as I forgot Red dead redemption, but to my defence I was only thinking of PC games when I wrote the list.

I have to include even more stuff.
Avernum series. Every ♥♥♥♥ one of them.

Man I loved that game! I haven't finished it yet though, but damn it's a very fun game to play.

Also, aside from most games named in here, I have to add Megaman 8, Megaman X4, Megaman X5, Megaman X6 and Megaman Legends 2. This games are awesome from almost any perspective, and man I love their music.

Also, Final Fantasy VII.

Get the ♥♥♥♥ out.

Forgot about Little Big Planet. It was such a great party game.

I loved Megaman Battle Network, and the Megaman Zero games. Beaten all of the BN's, and Zero 2, 3, and 4.