I can remember back in the days of the IBM 8088 personal computer, playing an incredibly simple game entitled Rogue. It was basically a dungeon crawler in which all onscreen objects were represented by ASCII graphics (much like Dwarf Fortress). Now, granted if you looked at this game today you'd probably think it was crap, but rewind three decades and your looking at an all time great and one of the first games to embrace the concept of procedurally generated levels.
So, I played the game for awhile. Had my fun, eventually got board with it and moved on. Much to my surprise I discovered many years later that this kind of "Rogue-Like" game (yes, that is a widely used term) still has a small but dedicated group of followers. Except now they're playing the aforementioned Dwarf Fortress or even titles like Brogue, which is also sometimes spelled "Br☥gue"...not sure why though. Anyway, the game is surprisingly addicting if you were a fan of the original Rogue. And even if your not Diablo fans might get a kick out of it. Remember that the Diablo series, particularly the first entry, was basically a rogue-like with an isometric view and beefed up graphics. Oddly enough I didn't enjoy Blizzard's attempt nearly as much as Rogue or Brogue. I'm not entirely sure of the reason, possibly because it's hard to beat free, but I think it also has to do with imagination.
You see...part of the appeal of 8-bit games and their predecessors (even in this day and age) is the open invitation to the player to fill in the gaps. Similar to when your reading a book you have to imagine the characters and places, so do you with these graphically simple games. Imagination can be (and often is) a powerful thing. It can lead to a kind of personal investment that is hard to obtain in more Hollywood style video games. Because, in a movie very little is left to the viewer to picture in his or her mind, but in a game like Rogue you are the painter and the game is just a canvas with a simple outline.