Diablo is a Rogue / Nethack clone
Naw I wouldn't go that far. It would essentially say that Nethack is randomisation and hack and slashing.
This is like those people who say Diablo is a MMORPG... (though I'd accept that before the above)
Well they nicked the format (from Angband, maybe Moria) and dumbed it down for the mass market, would you agree with that?
Diablo I has MANY more roguelike elements than Diablo II, so clearly showing the roots.
- Death is Real / no save scumming (without cheating). Though it allowed you to restart the game with the same character if you got stuck.
- Finite Monsters per Level / no level grinding / no unlimited item drops / no infinite XP - forcing you to play conservatively and think a bit, you can get "stuck" in Diablo I and it's too hard to continue, this never happens in Diablo II because you can level-grind on easier monsters.
- Square Map, descending to Hell
- Town / Shop Level
- Grid-based movement (and turn-based movement in early Alpha)
- Classes, but all players can learn all skills / spells
So Diablo I is clearly much closer to it's roguelike roots than Diablo II. Diablo II seems to have added telnet MUD ideas (like a modern MMO too) :-
- respawning dead players with loss of XP
- expansive areas which respawn set monsters
- level grinding / item grinding
- classes with unique roles and rules (e.g. tank , archer, mage etc)
There have been plenty of bad ascii roguelikes, eg Alpha Man or whatever it was called. Being a bad example of something doesn't preclude it being a derivative, or say anything about the original. e.g. Doom the Movie is a rip-off of Aliens (and others), very bad, but a clear rip-off.