Recommended games?

KotOR.

AC: Revelations
If you like the franchise like I do, it's a must-have.
Also, that first trailer, it's not a trailer. That's the game's opening sequence. My brain about exploded when I first cranked it up and realized this. True story.

Half-Life series for single player.
Counter-Strike, Team Fortress 2, Left4Dead for multiplayer.

This( yeah, I know, right now i'm suffering from the hype).

+1 for Kotor

Also Bastion,Braid,Machinarium if you are in the indie stuff

Galactic Civilizations 2

It is SO good. SOOOOOOO good. I haven't be able to get hooked on a game in quite some time but galciv2 has done just that. This game has nearly infinite gameplay. Your mileage may vary, but for me, it is amazing.

Check it

There are plenty of other great games on Steam, but I'm sure other people will cover most of them.

Recettear: an Item Shop's Tale - "Capitalism, ho!" Run an item shop in a fantasy RPG world. Go dungeon-diving to find treasure. Buy low, sell high, and gouge your customers--but not too hard! Can you make enough profit to pay off the debt?

Terraria - A sandbox game with metroidvania aspects. An immense world for you to explore and reshape and customize as you wish. Play with friends on a multiplayer server--save the world from endgame threats, or battle each other in PVP action! Even includes hat simulator action!

Crayon Physics Deluxe - Draw things that interact with other things. Use them to lead a ball to a star. Much better than it seems from just a description--it's a very nice casual game with soothing music and lots of room for creative solutions to problems.

Some really good indie games:

• Eufloria
• Night Sky
• Osmos
• Overgrowth (Alpha) (The animations are absolut awesome!)
• King Arthur's Gold (Alpha)
• Project Zomboid (Alpha)
• Voxatron (Alpha)

HALF LIFEEEEEEEEEEEEEEEEEEE

Sequence. I had a 12 hour love affair with that game, and am currently hoping they make a sequel

Skyrim game of the century :D

Batman: Arkham Asylum & Arkham City

Oh, you didn't say Steam only.

Here's a non-Steam game: Spelunky.

It's the only game where:

• being run over by a caveman is a real threat
• throwing a damsel into a snake pit may be a good idea, and
• yetis get to play tennis with your corpse.

Fable TLC

Skyrim

Mass effect

I would tell you to play Civ 5 and TF2, but you already play them. I would recommend Borderlands, Left 4 Dead and Torchlight.

Skrym, Saints Row: The Third, Terraria, Bastion & super meat boy.

Warcraft III Frozen Throne(expac) and Reign of Chaos(base game)
Diablo I, II, Lord of destruction(expac)
Starcraft 1, broodwars(expac), Starcraft II Wings of Liberty,
Dota( THE ORIGINAL IN WARCRAFT III) or Heroes of Newerth
Medieval II complete pack

I've been addicted to the F.E.A.R. series lately.

If you want to play a realistic RTS I would strongly recommend "Men of War" series. Graphics are bad but it's the best WW2 strategy I have ever played.