A Link to the Past/Super Metroid combo randomizer. Both games smooshed into a single ROM, with certain doors taking you from one to the other. Item pools are then shuffled together, sending you on a big scavenger hunt to find Metroid items in Hyrule so that you can explore Zebes to find Zelda items so that you can explore Hyrule.
Unfortunately it’s somewhat lopsided due to how much bigger ALttP is than SM, but the technical novelty of it is amazing and worth a playthrough.
Fallout UK
deleted by creator
The New Order: The Last Days of Europe for Hearts of Iron 4
Considering how opaque the game was for modding, I’d argue Hearts of Iron 3 BlackIce is the more impressive achievement
Mechwarrior Living Legends is a mod for crisis that builds a compltely new game ontop of it and had a thriving multiplayer community for many years (not sure how activity is these days)
Expanded Stardew Valley! So much added stuff!
Rounding out my top three for Stardew are the pause and teleport mods
Came here for this!
If you haven’t played Divinity Original Sin 2 with the Epic Encounters mod, you haven’t experienced the game to its fullest potential. Give it a try if you already love DOS2 and would’ve liked to see more! 🙏
Cataclysm: Darker Days Ahead.
Daily pull requests for over two decades on an open source project
Does pokemon infinite count?
Even without the gimmick of merging any 2 mons to create new ones with some procedurally generated art and thousands of community created ones; it’s the best Pokemon game since black/white 2 in story and hg/ss in scope.
I really liked the Custom Maps in Warcraft 3 online play. I used to play Hero Line Wars, Mauls and TDs, Dota, Legion TD among other amazing community made maps
Otis_inf’s camera tools. Blows away any in-game photo mode. No restrictions on movement at all, can pause or frame-advance the game, there’s even a camera rails system I haven’t fucked with yet.
Space Exploration for Factorio. My dude built a huge mod for free, then was hired by the devs to desogn the paid sequel, Factorio 2, and although large and great its still smaller and less complex then the mod.
Krasstorio 2 as well. Not as complex, but just as good and the sprites were better than the base game.
Caveat, I don’t play a ton of modded games, but Dwarf Therapist for Dwarf Fortress is such a good mod. Makes the game playable, lol.
I’ve never played it myself, but Gary’s Mod was all the rage back in the day.
Super Mario 64 that added lugi as co-op
