Just like the title says: Recommend me a rogue-like for Linux. Preferably one with a decent GUI. I'm not above playing some Nethack in a terminal but at the moment I'd prefer something mouse-driven and modern.

Tales of Maj'Eyal is pretty good

ToME is a great choice, and I'd second that. However, if you're looking for something a little less painful (and for all that ToME is amazing, and you should play it, it is so painful on Nightmare and higher) you might also try Dungeons of Dredmor, which is a much more light-hearted roguelike that will still kill you happily, but with less one-shot-from-out-of-line-of-sight nonsense.

I agree ToME is a good choice.

As for other rogue-likes... , [url=http://slashie.net/]CastlevaniaRL (maybe since it uses java, so...), , [url=http://diablo.chaosforge.org/]DiabloRL (Diablo 1, even allows hooking into the original cd data files to play music, sound and voice acting)

Hmmm...

Question on ToME, how random it is? Does it have level-scaling and/or can it be easily modded to have static levels? I heard level cap is 50 and that there is some high level cap mod, how good it is?

You mean the inifinite500 mod i think? That mod is more intended for going in the infinite dungeon than the main game, since otherwise the level50 cap will eventually kill you since the enemies just grow too hard after a certain point.

And yes it's level scaled, almost the whole game is. Although exactly how that works I'm not sure, more of a internals to look at.

BTW you can download ToME for free rather than buying it on GoG, the difference mostly being that on GoG you can get the DLC/expansion and the main site only gives the base game for free. I'd say, get the game, get the mod, and try it out for yourself. I honestly never got past level 20 so i am not sure sure how useful the infinite500 mod is.

Ziggurat and Risk of Rain are enjoyable.
You may get addicted.
I have played Risk of Rain for 1000+ hours.

Binding of Isaac: Rebirth.

Not a roguelike.

It's rogue-lite... a few random-ish elements, beyond that it's far more a topdown strafing simulator....

Or do i mean kiting...

Good game... I backed it :)

The battle mechanics are similar to Desktop Dungeons where you fight each individual monster you want to (unless they block your path). It's heavily based on it's original game which can be found as a flash game at various places, like Kongregate.

You owe me a new pair of pants because that game's trailer made a mess in mine! That looks amazing. Thank you!