'Inquisitor' is probably in the top 3 of most difficult games I have ever played, and I played the Priest class, which is supposedly the easiest. I started off being unable to hit anything with spells, so I got an early hireling that could tank pretty much anything for the first half of Act 1. By the time he started to burn through healing potions my spells started to connect and I was somewhat proficient at killing things if I supplemented my abilities with seals. Then comes Act 2 and there is a *massive* difficulty spike that is more pronounced than the one you get in Wasteland 2 when you leave Arizona and go to California. It's like hitting a brick wall where you encounter archers that kill your PC in two hits (and your hireling in one), and your spells have a 50% chance of even hitting.
It's a shame, since I loved the setting, story, and even the idea of the spell system, but the gameplay is hardcore.