[H] Nexuiz [W] Your soul, EPIC game suggestion. [Ended]

Frozen Synapse

Path of Exile is in open beta (free) and feels a LOT like what Diablo 3 should have been, frankly.
http://www.pathofexile.com/

oddworld abe's exoddus and abe's oddysee, you must try it!

Don´t Starve =) It´s still BETA but really fun to play...you´ll want to eat your keyboard or just bash it in your screen if you die again and again! Just learning by doing and it allows no mistakes^^

The Longest Journey. Play it. Play it now.

PIKMIN !!!

Binary Domain, I guess. It's a AAA game, yet fairly unpopular. Plenty of epic moments. Deserves more attention.

Gotcha Force for Gamecube. Greatest game I've ever played.

I just drop here comment

Dungeons of Dredmor is nice too, it's fun and hilarious...

What about a Magic The Gathering - Duels of Planeswalker game? Yeah, i guess you have to like TCG's to like it, but i don't know if you like it, so... if you do, you should give it a look, or two :)

scrapland, its not on steam. http://www.gamespot.com/scrapland/

Play Swords and Soldiers HD, I really enjoyed it even though I had never heard it before.

something cool to play...CRYSIS 3 OPEN BETAAAAAAAAAAAAAAAA I love the hunters mode . or play Mass Effect franchise or Arma 2 or League of legends or just simply screw the PC go and play Battle City and Super Mario or some Contra on the Atari.

Knights of the old republic 1 and 2 or jade empire

Deadlight

If you're looking for simply multiplayer fun:
Pirates, Vikings, and Knights http://store.steampowered.com/app/17570/ (free source mod and it hilariously fun)
Hidden Source http://www.hidden-source.com/

Kung Fu Strike

I ran out of souls, sorry!
Try Soldat, not on Steam. I hope there's still a small community for it, it was definitely a fun 2D shooter ^__^
If you haven't played Alien Swarm (Steam F2P) I definitely advise that.
In terms of Beta games, Path to Exile and Don't Starve would be my top two choices.
If you're into Mechs, try Mech Warrior Online (non Steam F2P)
Also you've probably heard of Planetside 2, but it's a super good F2P FPS

Try playing Toribash - it's a free game, iv'e been addicted to this for some weeks :D http://www.toribash.com/

hmm maybe one of the dawn of war games? :D like dark crusade :D

I just started playing borderlands 1 :) and am starting to get back into day of defeat source ^^

well from the less known it could be State of War, Bet on Soldier or Knights of the temple

Streetfighter games are nice, too, idk if you got it for any console or if you don't like it, but yeah lol
And Call Of Cthulhu: Dark Cornsers Of The Earth is also a nice game if you like the stories of Lovecraft or horror games :)
Cube 2 Sauerbraten would be a nice f2p game if you don't know it ^^

install the hidden source beta mod, it's pretty fun or try the last remnant

Audiosurf...