Use Desktop Mode first

Steam Deck setup is much easier in Desktop Mode. File browsing is clearer, Java launch paths are easier to debug and the Proton save location is far less mysterious when you can inspect it like a normal desktop.

If you are still deciding which package to use, the Download page gives the short version: on Deck, the JAR route is usually the cleanest starting point.

Keep the save path visible

The normal Proton route lives under:

~/.steam/steam/steamapps/compatdata/275850/pfx/drive_c/users/steamuser/AppData/Roaming/HelloGames/NMS

Do not rely on memory for this. Copy it, bookmark it or keep the save-files guide open while you work. Most Deck frustration comes from path confusion, not from editing logic.

Launch the JAR, then test something small

Once Java is working and the editor launches, do not jump straight into a large repair or customization session. Open the save, make one small visible change and confirm it in game.

That test tells you:

  • the JAR launch path is working,
  • the save path is correct,
  • the editor can write back to the file you opened,
  • and the game is reading the same save afterward.

Common failure points on Steam Deck

Deck workflows usually fail in one of these places:

  • the JAR never launches because Java is not set up cleanly,
  • the wrong Proton prefix is opened,
  • the right prefix is opened but the wrong save folder is chosen,
  • or the user arrived right after a game update and expects brand-new content to already be mapped.

Treat those as separate problems. Do not debug all of them at once.

When to stop and check compatibility

If the editor opens and your save loads, but the exact item, reward or new patch content you want is still missing, that is not a platform-install problem anymore. That is usually a compatibility or mapping question.

At that point, move to: