Remove Wizardry (NES) and cycle in Wizardry IV. That game is bullshit.
Exile: Wicked Phenomenon gets an honorable mention not so much for being difficult as it does for being fucking bullshit. I guess "hardcore players" would find the allure of endlessly grinding away their levels on short side scrolling segments to get to the point where bosses don't kill them in one or two hits appealing, but I found the game to be a tedious fucking mess of Vic Ireland's bullshit. Apparently the japanese version is a lot more playable, not that I'd ever want to try since it's such a drastic step down in quality from Exile any-damn-way.
But yea. Fuck Wizardry IV. Have fun reading the wikipedia article.