Tetrinet… Why play single player Tetris when you can be in a Tetris orgy? Use power ups to destroy weaker Tetris players and defend your precious lines.

Get the drop at http://tetrinet.info/ Available for PC and Linux.

Dungeon Crawl Stone Soup… Play this Nethack roguelike and die, play some more and die a little less.

Die at http://crawl.develz.org/wordpress/ Available for PC.

Nethack… You will die a lot in this randomly generated dungeon game. More addicting than Christianity.

Right here at http://www.nethack.org/ Available for PC and Mac.

Dwarf Fortress… Create a living, breathing kingdom in this survival game. If you don’t like the ugly ASCII graphics you can download pansy tilesets.

It’s here at http://www.bay12games.com/dwarves/ Available for PC.

Soldat… It’s amazing that the Polish have spent time making a great 2D multiplayer shooter instead of doing manual labour.

Give it a go at http://www.soldat.pl/en/ Available for PC.

Armagetron… Remember how cool Tron was? Well play the only cool bit from the movie online with other nerds with this game.

Get it at http://armagetronad.net/ Available for PC.

UnReal World… If you dream of being a fat, nerdy Bear Grylls or in other words, Ray Mears, you can in this RPG allowing you to survive in the harsh wilderness.

Get it at http://www.jmp.fi/~smaarane/urw.html Available for PC.

Spelunky… It’s a mix of stealing cursed treasure, sacrificing small animals and dying.

Check it out at http://spelunkyworld.com Available for PC and due out for XBox Live Arcade.