For those who want a less grim and dark turn-based rogue-like RPG, there is actually an equally good alternative to Darkest Dungeons; it's called Shattered Planet. Instead of traditional turn-based gameplay, Shattered Planet is a bit more like Crypt of the Necrodancer meets Pokemon.
Every turn happens at once for everyone, and you can queue multiple move orders at once, making the game feel almost like a realtime experience. However, once you are in combat, you fight whoever is immediately next to you, and while you can retreat, there's very little reason to.
The game has multiple objectives to aim for, be it getting further into its levels, exploring story-based missions, or just trying to find as many unique items as you can. Everything rewards you, keeping a constant feedback loop like out of Diablo.
The biggest deciding factor you have to go with is whether you want the game for free, or with bonus content. The PC version includes bonus content and a much more fair economy system, but also costs $14.99 despite simply being a rogue-like. However, the tablet version of the game is much more grind intensive. You'll have to make the call on this one.
If there are any other fantastic budget RPGs you can think of that I missed, be sure to let me know in the comments below!