Yep, I'm having a retro attack right now. Game (System) Glitch Name: Why it can be game-breaking/damaging: Donkey Kong Country 2 (SNES) Castle Crush Glitch Can cause loss of save data, and even potentially alter the rom itself. Yes, from my understanding it also affects physical catridges as well, so don't try it on a real cart kids. I certainly won't. In fact here's a youtube video outlining how it's done, and 8 Minutes or so showing various side effects it causes. Most often, it will cause save data loss, but there is still a good sized amount of potential for the rom in the physical cartridge itself to be damaged. Secret of Evermore (SNES) Lose the Windwalker and get stuck. When you aquire the Windwalker if you travel to the bottom left of the screen as far as you can go, and attempt to land in different places eventually you will land then reappear in tinkers tower minus your ship. This causes you not to be able to complete the game, as you need the Windwalker to go back to Nobilia to get the Diamond Eyes from Tiny in the pyramid, the guage from the volcano in Prehistoria, or anything else needed to use the shuttle to get back up to Omnitopia. Secret of Evermore (SNES) Dangerous Gate Glitch in Tiny's Pyramid When you go to get the Diamond Eyes, you have to go to Tiny's pyramid to get them from him. However, once you've opened the gate leading to Tiny if you try to leave at any time after opening the gate but before the boss battle and obtaining the Diamond Eyes, the gate will slam shut permanently. Meaning you won't be able to get the Diamond Eyes from Tiny. Which means you cant beat the game unless you use this glitch below. Secret of Evermore (SNES) Get another Guage Not really a game-breaking glitch, rather the complete opposite. Get the Gauge from the Volcano, then leave the area. Now return to the Volcano and there will be another Gauge for you! Even more surprisingly, this Gauge actually acts as if it were the Diamond Eyes! Fixing the glitch above Pokemon Red/Blue/Green (GBC) Stuck in Glitch City Not so much gamebreaking just by itself, but if you save inside of glitch city without any Pokemon that knows Teleport or Fly you will be stuck there forever which is what introduces the game-breaking aspect to it.