If you played Titan Quest back in the day, this is basically Titan Quest. Only WAY better than Titan Quest.

Lemme explain:
It's basically Titan Quest in that a LOT of the mechanics are the same; you pick a second subclass (or 'mastery') at level 10, you get multiple skill points/level but you also have to invest some of them in the mastery itself in order to unlock higher level skills for that mastery (doing so also gives you stat increases), a lot of skills are passive buffs to earlier skills in the tree, there are a fair bit of skills that reserve energy (they stay on, but instead of being passive they reserve a portion of your energy bar that can't be reclaimed until you turn off the skill), equipment modifier items (gems, i.e.) can be stacked & give a bigger bonus when a stack is completed, and they're also used as crafting equipment; you need to find recipes for relics, you can't find relics in the wild.
Oh, and the maps aren't randomly generated, so prepare to get VERY familiar with the locales. (They're not as long and boring as in TQ, thankfully.)

BUT! It's way better, mainly because the engine this time around is a lot smoother & faster. Going back to TQ recently, I forgot just how slow and PAINFUL the combat in that game was. Here it's a LOT smoother, and it's shocking how much of a difference that makes.
Also, there's a health recover mechanic; you recover all your HP at the cost of "constitution", which you restore by finding food rations in the world.

Disclaimer: I Kickstarted this game. I'm not sure why. I'm glad it worked out, though!