Hideous Destructor is a gameplay mod for Doom that makes the game become a lot more harder, and a lot closer to real life, than vanilla Doom. You now walk at a normal speed, instead of being a rocket powered wheel chair. Bullets drop because of gravity. Rifles have scopes. And the rifle ammo magazines are proprietary as heck, if you load an used magazine you'll void your warranty. Some people despise this, but I for one enjoy fighting for survival in a world where a zombie can kill me in a few shots, and I enjoy deploying DERP bots and sneaking around corners, and trying to always be the first to pull the trigger.
When I first discovered Hideous Destructor, I tried to play it in Freedoom and there were too many visual glitches. Freedoom zombies would become Doom zombies upon death. The shotgun would become the Doom shotgun while it reloaded. There were too many modified Doom sprites.
Today I decided to try HD with Freedoom again, just for kicks. So far, I haven't found any of these glitches! Now I can experience Freedoom Phase 2 in a slow, hyperrealistic fight for survival with a double barreled shotgun whose spread doesn't cover half the screen and is in fact the same spread as the other shotgun.
Thank you, MatthewTheGlutton, for making Hideous Destructor cross-IWAD compatible.