Herculine's Doom Upgrade is a mod for GZDoom that uses custom spawners to randomize monsters and items. Many new ones are added and have been carefully selected and placed to present new and unexpected challenges while attempting to maintain a semblance of the original difficulty intended by any given map's author as well as to maintain the original atmosphere of the games. New weapons have also been added in an attempt to maintain these balances but also have been chosen to fit the original atmosphere.
As a result of randomizing monster and item spawns, difficulty can potentially be erratic. Overall difficulty is usually slightly higher. If you're having too tough a time of it, you can try restarting the level to get a different set of random spawns.
This mod likely will not work with any mod that replaces the existing monsters, weapons or items. This mod will work with any Doom IWAD and should work with most custom megaWADs and levels, but may not work with heavily scripted ones.
The various contributors to Realm667's Beastiary, Armory, Item Store and Prop Stop. This mod is in no way an attempt to take credit for anyone else's excellent work. A full list of credits can be found in texts both included separately with this WAD and also imbedded in the WAD itself.
Snarboo for his randomizer which inspired me and taught me how to do this.