I know only 2 multiplayer roguelikes: Incavead and TomeNet. Pathos' developer is working on multiplayer (co-operational if I remember correctly) just now. And I heard about Rogue Element RPG, but I haven't played it.
Creating multiplayer roguelike is really tought task, especially if you want to support network multiplayer. Local multiplayer is more viable option, but you need to work on it from the very beginning - some usually secondary things, like designing ui, menuses, controls, would become first-tier issues. Also, you will need to spend much time on testing - how enjoyable is your game for specific number of players.
If you are asking for my preferences - definitely offline single player.