I have it from GOG, but like the Crypt Of The Necodancer.
It's a roguelike, in which you have to beat the monsters according to the rhythm of the music !
It's really fun , despite the fact that my char has died during every session.
The only negative of it is its loading time. That's quite long !
Quite challenging is the Mages Of Mystralia, a fun looking game with an imho huge learning curve : You can get new spell components through challenges. And you can win some challenges only with certain spell components …
You combine them to get better and sometimes VERY different spell effects !
And you need them. Definitively.
If you want something very different, then you could try Rollers Of The Realm. Nice voiceacting, although there are not many characters + NPCs, a good learning curve, and your characters are played like balls in a pinball game !
Its only drawback is that one has to watch the intro of each fight every time one fails.
Giana Sisters, the remake, is a graphically very good jump & run game, with a good learning curve, imho. It becomes more difficult in later levels, though.
Yoku's Island Express plays like a pinball game and it's difficult from the beginning on.