When I try to launch this, all that happens is my computer slows down and I hear piano music for a few seconds.
Yes, I meet the minimum requirements listed on Steam. Yes, I've tried the Steam version, and the same thing happens.
There's no way to fight the wizard EVER if you choose to give him the crystal even once - dying and respawning after doing so leaves you unable to shoot fireballs.
This is even more of a problem than it seems considering that the 'give crystal' option is the top one, so it's what you'll hit if you mash spacebar to get through the dialogue.