So I was reading the "Ever broken a Game at it's own Game?" thread and thought about glitches/ bugs that don't exactly HELP you but the opposite. They make the game totally unplayable more than often unbeatable and if you don't have a save before the bug or you found out the bug after you have overwritten your only save, well, then you're fucked.
Hexx: Heresy of the Wizard
An old DOS RPG (pretty awesome BTW). It had one of the shittiest bugs I have ever encountered and I lost 6 hours of playtime to it. Basically the game is your typical dungeon crawler with locked doors, traps etc. Some of the locked doors can be opened by special keys (like in the Eye of the Beholder series) while others can be oppend by so-called COMMON KEYS.
Common Keys can be bought in shops and found in the dungeon.
sometimes while going to an upper/ lower level via stairs/ teleport/ pit hole you would lose ALL the Common Keys in your inventory except one.
It was not a big deal if you found yourself in a level with shop but I encountered it after falling down a pithole to a level without a shop. And the only way forward was closed behind 2 Common Doors.