Divine Divinity is by far the best old school hack n slash game if you dont count the diablo series. Imo its better than divinity OS, I dont really enjoy turn based that much after discovering hack n slash.
Nox is another little known game that was actually pretty good back in the day, not forgetting sacred 2 of course another classic (please dont even look up sacred 3). Theres also Van helsing, imo Victor Vran is a better game, but you said old school right? So dungeon siege 2 might fit the bill i enjoyed it more than pillers of eternity tbh.
Or there is another game ive followed for years but never really got into to much, called Exanima.
Im sure there is a few more old ones ived played and just cant think of there names. Any way hopefully there is a game here ive mentioned to get you some good gaming hours in, there pretty much all solid games, more or less.