I just wanted to bring attention to not only the entire Wizardry series but specifically Nemesis: The Wizardry Adventure.
Nemesis to this day still sets many of the standards I measure an rpg by.
I only see 4 votes for it even though there's over 100 for each of the normal Wizardry series. I have to say, any Wizardry fan who hasn't tried Nemesis should. It's not the same style as the normal Wizardry series and has a completely different story but, to me, that puts it as a valuable rare gem. As with any game, I can't guarantee everyone would like it but it's a game I would recommend to anyone.
The only two Wizardry games I've played is Knight of Diamonds on the NES (loved it) and Wizardry 8 (loved it as well). I'd like to see any and all of them here on GOG.
I'd also like to put my vote for Arcanum: Of Steamworks and Magick Obscura, and Planescape: Torment. While neither game is very polished, the amazing atmosphere and setting and story make both of these games must-haves for any lover of old-school RPGs.