Balls! there are a lot of games on that list...
Must have games:
Vampire: Bloodlines - Really excellent action RPG. I believe it has its own thread somewhere on the forums.
Terraria - Build and craft blah blah, if you don't know about it read the giant thread here.
Plants vs Zombies - Great casual game, good helping of humor. Many hours of fun to be had.
Good games:
Overlord - Definitly not free of issues and clearly not a game about being evil. First one actually had a really awesome story and twist, second one is more of the same. Almost a puzzle/action/strategy game.
Left 4 Dead - Good co-op fun, hilarious being the infected
Bioshock - Nothing ultra-special for a first person shooter, but a fun game none the less.
Borderlands - Another some what run of the mill shooter. Some annoying bosses but generally a good time. Better with friends.
Just worth the money:
SPAZ - This game is mostly a grind. You do a lot of the same thing over and over trying to get the exact gear you want. The humor is hit or miss and the plot twist is kind of meh. Still fun and worth 11 bucks. Suggestion; play on a smaller galaxy. If you play on a larger one you'll only explore 1/3 of it.
Zombie Driver - Really a meh game. Mindless fun.
Games people will disagree with me on:
STALKER: Bad. I didn't like this game at all. It was slow and clunky and often hard to tell exactly why things were happening. It never sat right with me. It is like they were aiming for an Action RPG but took out almost all the fun RPG aspects (like leveling and trading for sweet gear) but left in the travel time and funky controls.
Dungeons: Good. Fun theme park constuction game. A lot of people get hung up on the fact that you have to make heroes happy just to kill them. A lot of people expected Dungeon Master + Tower defense. In reality it plays more like roller coaster tycoon.