Exactly what the title says.
What good free games can I get?
Please post.

Surgeon simulator is cool

The full version is just phenomina.

Nitronic Rush.

Aside from toribash...

Team Fortress 2 (steam)
Tricky Truck (check it out)
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Tribes:Ascend
Microsoft Flight (Fun)
If you have any valve game that uses the source engine there are plenty of good free mods.
mari0 (Mario and Portal Mixed)
And there's always console emulators (NES, SNES, N64, Game Cube) but downloading games for them is illegal. So I do not propose you do this. I am only answering your question of "good free games".

League of legends

Osu! (skill based music rhytmn game.)
League of Legends (Moba/dota based game.)
Teeworlds (2D online shooter.)
Path of Exile (Hack and slay, like diablo series.)
Stranded II (survival game, not like minecraft. bit more complex but with less stuff to do. got a story etc.)
Warframe (shooter, didnt played much so cant explain further.)
Battle for wesnoth (round based strategy game, is great, i love it.)
Grand theft Auto 2 (there are also other websites which give a download link away, if u dont want to put your email there. also yea just the good old GTA2, 2D but lots of fun.)

thats so the stuff what i found in my games folder.

Cave Story.

Shotgun FunFun is addictive. You're basically just shooting zombies in a 2d scroller. Kinda pointless, but fun.
Dunno if it works with Windows, i think it does actually, but i got it from the App Store.

Then there's Pulse, you play as a blind girl, who throws cute little things which makes sounds when you throw them, which is your only way of seeing. Pretty fun actually.

Dwarf fortress, can't really say much about it though, i'm kinda new to it.

AQW was fun for a while, when i played with a friend, but i quit. It is a bit silly.

There's also some nice flash games. Super Meat Boy, Time Fcuk (same author btw), the Grow series, Infectonator (World Dom is also fun), Achievement Unlocked series, Sift Heads series.

Yeah i don't really have much, i'll add more as it comes to my mind.

Everyone forgot about the Sonny flash game series, which you can find on armorgames.com

Oh yeah, that one was good.