Nethack

[General Grievous]

Nethack, from portableapps.com is a free app that isn't exactly save-file portable, but once you start playing you'll not mind.

Once you die you die in this 1985 game, with updated "tile" based combat for *windows*, (can't remember if Linux is supported, but it does have a text-tile version out there somewhere, but it's worse graphics). What isn't exciting is the graphics of the game. However, it truly is amazing in it's depth. Each time you play the game things change. You might be sucked into it super hard, constantly looking at the Nethack-wiki if your like me. I've been playing this game for a week or more now, and it truly is a masterpiece. You'll need guides and "spoilers" to do well most likely, but it is truly amazing to me, with many classes of characters to choose from, which may often vary in their starting items a little each time, and the entire world over usually changes as far as items and most monsters.