Path of Achra. Only recently found it and I love it. Roguelike, turn based, classic. About 2h for a full successful run. But every run it gets harder, up to 32nd difficulty.

Lots and lots of build combinations as it has races, classes & religions, pick one each and the bonuses are substantial. And 3 out of 9 skill schools. Item bonuses often scale crazy good with very specific style of play etc.

It's the kind of game that gets broken easily and it actively encourages you to do it, cause endgame bosses are no joke too.