My vote goes to Dungeons of Dredmor. It's a fantastic modern roguelike that has pretty amazing mod support, only adding to the replayability. And best of all, you can turn permadeath on or off depending on how much of a true roguelike experience you want.

If you dont have borderlands yet, and you like fps open world games, get it now! It's on sale!

But normal priced games under 10 bucks?
I'd say terraria or DoD, but if I have that 10 bucks, I'll buy call of cthulu:dark corners of the earth!
Good old game...

How about quake live or wofenstein enemy territory... well below $10 (free actually)

Got fallout nv(9.99) and bio shock 1/2 (9.99). During the sale.

Soooo many future hours of my life committed to waste lol

The Polynomial

knights of the old republic

Terraria

The Graveyard

SW: Knights of the Old Republic
Dragon Age: Origins

Need For Speed: Hot Pursuit

Bought for $2,5 during summer sale

id say fallout3 or the witcher.

Portal and portal 2,if you count sales.Best story,best scenerio,and of course,best lines from GLaDos!

Dungeons of Dredmor.

Super Meat Boy.

First Deus Ex. An incredible game.

im gonna get hated, but binding of isaac+dlc seems quite good

Ys: Origin if you count discounted price.

Otherwise... I don't know ._.

borderlands goty

X-COM: UFO Defense.

Shank

Killing Floor .. hands down ..

Borderlands: Game of the Year at the moment. :D

Killing Floor when it was on sale.

Terraria. Awesome game for sure. ^^