Wizardry: Labyrinth of Lost Souls

[briareos_kerensky]

The 4th's difficulty is usually described as legendary, so I've never tried it for more than a few minutes.

It is. You play as an evil overlord going up and obviously you have to fight powerful heroic parties. You don't fight directly but by summoning monsters and casting very few spells; summoning and healing can be done only in specific tiles and enemies per floor are a fixed number, however they are extremely powerful and all enemies respawn when saving. So, yeah, you can make the game unbeatable by saving.