Currently I can't really play Single Player Games.
But I like some kind of roguelike genre. Because most of them are unforgiving.

Somecommon features:
- Permanent death — games can't be saved/loaded, and death means you must start from the beginning of the game.
- Procedurally generated levels that are wholly unpredictable.
- Relatively high difficulty, with frequent deaths and short runs.
- It's a dungeon crawl, which takes place by progressing along rigidly defined 'levels' of the cave.

Here, you have a list of less or more roguelike:
FTL
Dungeon Crawl Stone Soup
Dwarf Fortress
Tales of Maj'Eyal
Rogue Legacy
Risk of Rain
Rogue's Tale
ADOM
Brogue
Doom: The Roguelike
Teleglitch
Shattered Planet
Dungeon of The Endless
Sword of the Stars: The Pit
Dungeons of Dredmor
Desktop Dungeons
Pixel Dungeon
Nethack
Spelunky
Don't Starve
The Binding of Isaac
Project Zomboid
Sunless Sea
Terraria
Starbound
Minecraft (:P)

http://www.roguetemple.com/2014/06/19/2013-ro...y-results/
http://forums.roguetemple.com/irldb/

I can recommend: FTL, DCSS, Dungeon of Dredmor, Spelunky. TOME4, Spelunky...
Imo Doom: The Roguelike can be on you will like :P Dungeon of Dredmor could be good choice for 1st one.

Spelunky looks like funny and easy game, but trust me, its hard. But someone can argue its not roguelike enough.

Didn't play them all, but I want to try all of them ;)

anyone played something decent?

Recent games are Sunless Sea and Shattered planet.