I was first introduced to Angband - and Roguelikes in general - via ZangbandTK. Its mouse-driven, graphical presentation served as a less painful transition into this arcane but passionately-followed genre. Over time though I grew to prefer the pure ASCII version, though I can't quite put my finger on why. Perhaps it was because as I learned the game and the array of commands I preferred the immediacy of the keyboard.
In any case, Angband presented a revelation to me. It offers all the compulsive elements of an RPG (character-building, exploration, strategic combat, and an obsession with '+' bonuses on items), while cutting out all the bloated stuff that often comes with them. There's no overworld, no tiresome townspeople to wring information out of, no sappy love stories or contrived plotlines, no bosses to spend hours levelling for. Don't get me wrong - sometimes those things are welcome, but sometimes I just want to sit down and kill lots of monsters in a dungeon.
That's not to say there isn't depth here, no siree. Angband's couple of megabytes of code certainly aren't taken up with the graphics and sounds. The level of detail in everything that's bubbling below the surface is staggering. Behaviours of creatures, effects of items and spells, and the player's own chosen profession present an enormous range of possibilities and events. Add to this the fact that the dungeon levels are randomly generated every time you move up or down a level and you have a game you can essentially play forever.
It's hard to explain the appeal of Roguelikes to someone without them actually trying them - and even then it's going to be hit or miss whether they take to them. I was immediately smitten, as I stumbled into the genre at a time when I was really looking for something new. Funny that I found what I was looking for in one of the oldest games around.