I haven't played any computer games in a couple of years, but I remember I used to have this game called Heretic II. It was quite hard, but then I got to the last level, which I found literally impossible. The main bad guy who you're supposed to assassinate has locked himself inside this force-field thing, which is powered by a number of magical books (it's fantasy). The idea is, you have to go around his castle searching for a bunch of switches; each switch closes one of the books, and once all the books are closed, the force field goes down and you can kill the bad dude. I think I managed to find two or three of the switches, but the rest eluded me. I did everything I could - I read internet game walkthroughs, I brought friends over to help me search for them, I even used a cheat which lets you walk through walls, but I still couldn't find the other switches, and have no idea where they are to this day! Would anybody happen to have played (or, better yet, finished) this evil, frustrating game by any chance?