So what's a Rougelike ?
The roguelike is a sub-genre of role-playing video games, characterized by randomization for replayability, permanent death, and turn-based movement. Most roguelikes feature ASCII graphics, with newer ones increasingly offering tile-based graphics. Games are typically dungeon crawls, with many monsters, items, and environmental features. Computer roguelikes usually employ the majority of the keyboard to facilitate interaction with items and the environment.
And why is it so fun ? Infinite replayability, hundreds of Race/Class combinations possible, hundreds of items to collect, and tears on your cheeks because you died just before last level.