Having heard a lot about the game and then discovering it was available for Mac, I picked up Darkest Dungeon on Steam.
Darkest Dungeon is an RPG with an ever-rotating cast of party members, because any character that dies dies permanently. The characters themselves aren't really major draws - they're randomized members of stock classes like "Crusader," "Plague Doctor," and "Grave Robber."
The main draw of the game is that, in addition to monitoring the health of your party as they fight their way through the horror-filled ruins you, the faceless, non-participatory protagonist, inherited, the act of dungeoneering causes stress that can manifest in problematic personality traits and even give character heart attacks.
Many enemy attacks assault the mind more than the body, and some of these personality quirks can wind up really interrupting your strategy to keep the team alive. For instance, one of my party members was paranoid, so he refused to accept a buff that another party member wanted to cast on him out of fear that it was a trick.
Resources are limited in a survival-horror kind of way, so while you can spend money to have your party members hang out at a tavern or an abbey to reduce their stress levels, that means less money to provide food, torches, and other supplies you'll need on your expeditions.
Torchlight plays a big part in making your group effective, and while you might stock up on a lot of torches, the light fades quickly. Bright light seems to let your party surprise foes while if you let it get dim, your party will just get stressed out and often be on the receiving end of those surprises.
The aesthetic of the game is also a big draw. The characters and environment look like they're part of a Mike Mignola comic like Hellboy. You can customize the look and names of your party members, though I recommend just switching the color palette to help identify which Bounty Hunter is which. Don't get attached.