Recommend Desktop Dungeons, the full version is great but the alpha is free and can give you an idea of whether you'd like it or not. If you're after a rogue-like and not a rougelike there's no shortage of options (vast majority of which are free). Best on Steam is Tales of Maj'Eyal, but you can also just get the free version from their website. Other good ones that aren't on Steam are Dungeon Crawl Stone Soup and Brogue.
Desktop Dungeons! A buddy of mine suggested the game to me during the sale but I had forgotten about it, i'll likely check it out later this week. Hopefully they put out the 'planned' linux port soon (like Paranautical Activity!).
I've played endless hours of DCSS and enjoyed it a ton, i'll look into Brogue.
Thanks!