Darkest Dungeon

Darkest Dungeon is sort of like a D&D campaign with the most vengeful, hateful, vindictive DM ever to walk the face of the earth. You control around 20 heroes, and must lead them in their quest to purge a small hamlet from the Lovecraftian horrors inadvertantly unleashed by your ancestor.
I don't feel like this description does the game justice, but it's basically a realistic roguelike dungeon crawler. Here's the website link and here's the Steam store link.

 

Darkest Dungeon is a really good game. It's somewhat pricey, but its totally worth it. The monster designs are some of the nicest things in the game. (Along with Wayne June's wonderful voice.)

Here's a Let's Play by BaerTaffy if you wanna get a taste for the gameplay.

 

Something I didn't mention is the Stress mechanic, which is arguably the most important gameplay mechanic, and definitely the most unique one.
Basically, doing anything at all while inside a dungeon has a chance to raise a hero's stress level, and once it reaches 100, they get a really bad debuff, that usually results in all of your heroes taking more stress and damage. If it gets to 200, they suffer a heart attack, which will drop them to 0 HP, or kill them if they're already at 0.
Trying to manage stress both while in a dungeon and by trying to cure it in-town is definitely one of the most fun parts of the game.