Another one worth trying if you haven't: The Binding of Isaac. Quite fun and addictive (ask onetrueijed about it). 

473 hours and counting. I planned on quitting once I hit the 400.0 mark but old habits die hard. 

is veritably amazing. So is Keyboard Drumset Fucking Werewolf, though in a different way. 

Thanks guys. I'll add The Binding of Isaac and KDFW to my list. I plan on taking the ones with shorter campaigns first. Currently playing Cave Story (for the first time) and replaying Harmony of Dissonance on PSP (through a GBA emulator which works surprisingly perfect). Also had half an hour with Metroid: Zero Mission (via the same emulator). 

Isaac: 521 Hours, but I stopped playing some time ago.

Indie games not already mentioned;

Weird Worlds is indeed a great space exploration roguelike, it's nice to see they're working on the third version.

Another space explorer roguelike I can recommend is Faster Than Light.

Spelunky - an oldie but a goodie. Platformer roguelike player rape.

Desktop Dungeons - haven't looked at this in quite some time, but a limited space dungeon crawl roguelike where exploration regenerates you.

Cthulhu Saves the World - breath of fire style RPG.

And I'm probably forgetting many more. 

... can quickly become overwhelming! :D 

Any idea how simular Metroid: Zero Mission is to Metroid: Fusion? Because I loved that (until some boss that made my emulator crawl). 

Metroid Fusion is a lot more linear and directed, until the very end when you get to explore freely for some time.
There is an annoying NPC that you are forced to talk to inbetween setpieces.
Other than that the gameplay is still the same old good stuff, and there are some cool environments. 

xxx 

i liked zero mission more, fusion forced too much linearity onto the player. But fusion is still pretty good in other respects. 

http://www.youtube.com/watch?v=l3LGb8EwhTU

FUCKKKK!!! FUCKKK!!! oh my shit!! This is absolutely the best thing I've ever seen, including vaginas and the bugatti veyron. 

DAT TRAILER!!! OMG!!! 

That shit is fuuuuuuucked up.

Looks good though. But how come Far Cry 3 Blood Dragon has nothing to do with fucking teenagers and cheesy mexican drug barons? It's like a TC, rather than DLC..... 

http://teksyndicate.com/news/2013/04/11/far-cry-3-blood-dragon-all-over-internet 

hope that doesnt mess up their sales. Really hope they get rewarded for being this wildcard. 

I got FC3 on release :) 

Many thanks. Those will be added to my 'check out' queue. 

http://www.youtube.com/watch?v=jAMI0fiJqY4

Does look nice :) 

Metro 2033 was a flawed but brilliant game with an awesome atmosphere. Very much looking forward to Last Light.

Shame about the stupid DLC nonsense from 4A Games though. They put the "nightmare mode" difficulty behind a DLC pay wall, and considering it's "the way the game was designed to be played" that's a pretty dick move :/

I'm expecting modders to unlock it for everyone pretty fast however :) 

looks awesome. i haven't played any metro's yet though. 

I haven't played any Metro games either, but that sure looks sweet! And Stalker is on my fav games of all time list. 

Then I think you need to play Metro 2033. Very similar atmosphere but a much more directed experience (read : linear levels rather than open world-ish that stalker had). 

But I hated Metro 2033. 

Metro was nice, but after playing Stalker, and reading a bit of the Metro book, it really makes you wish it was a bit more open-ended.
Still better than any silly CoD solo campaign.
Will probably get the new one myself, looks nice. 

Ranger Hardcore is the way to go if you want to tackle Metro 2033 the best possible way. No HUD, scarce resources and bullets hurt like a bitch. I played it like this on my first playthrough and had a blast.