Choose the game’s loader
Use tModLoader for Terraria, SMAPI for Stardew Valley, or Everest for Celeste. For Stardew dialogue and texture changes, start with a Content Patcher pack.
.NET / XNA / FNA
Terraria, Stardew Valley, and Celeste have established loaders. Start with the one built for your game.
Read the original playbookExisting loader → one small content mod → in-game test
Identification clues in a local game install:
FNA.dllMonoGame.Framework.dllContent/*.xnbFROM IDEA TO TEST
A practical first workflow
Isolate one experiment
Back up your saves and make a test world. In tModLoader, use a separate save directory. Add one item with placeholder art before expanding it.
Build, launch, and inspect
Use the loader’s build workflow and logs. In tModLoader, Build + Reload lives under Workshop → Develop Mods. Check that your item actually appears in the test world.
What can trip you up
- Check the installed game, loader, .NET, and architecture versions together.
- Keep decompiled reference material local; distribute your own code and assets.
MAKE IT YOURS
Start with this prompt
Adapt the game and idea to your own copy. This is a planning prompt, not a promise that a mod will work on every version.
Use universal-modder to plan a small Terraria mod using tModLoader. Search existing field notes, verify my installed versions, and propose one test item. Back up saves before changes. Ask before installing a loader. Start with placeholder art and verify the result in a separate single-player world.Games in this family
Unofficial guide · universal-modder by rehan-remade, MIT · Reviewed October 4, 2026. Source: upstream engine playbook.