Steam Deck modding: how to install mods by hand

Most PC game mods work on Steam Deck. You install them in Desktop Mode, the same way you would on a Linux PC. This guide covers the parts that trip people up: getting the files onto the Deck, finding the right folder, folder casing, and getting back to a clean game if something breaks.

Before you start

• Check the mod's instructions. Texture, model, audio and config mods are usually "copy these folders into the game folder". Those are the easiest on Steam Deck.
• Check for a loader. Some mods need a script extender or a DLL loader (often a dinput8.dll, winmm.dll or version.dll file). Those need one extra Proton setting, covered in step 6.
• Keep it simple at first. Install one mod, launch the game, check it works, then add the next. When something breaks, you'll know which mod did it.

1. Switch to Desktop Mode

Press the Steam button, then Power, then Switch to Desktop. A USB-C hub with a keyboard and mouse makes this much faster, but the trackpads work: the right trackpad moves the pointer, R2 clicks, and L2 right-clicks. Press Steam + X to bring up the on-screen keyboard.

To go back later, double-click Return to Gaming Mode on the desktop.

2. Get the mod files onto the Deck

The simplest way is to download the mod in a browser in Desktop Mode. It lands in ~/Downloads. If you downloaded it on your PC instead:

• USB drive: plug it into the Deck (through a hub or USB-C adapter) and open it in Dolphin, the file manager.
• Over your network: KDE Connect is built into the Deck's desktop. Apps like LocalSend or Warpinator also work, installed from the Discover store.

Most mods come as a .zip, .7z or .rar. In Dolphin, right-click the file and choose Extract. Then look inside: you want the folder that matches the game's own folders (like Data, Mods or BepInEx), not a wrapper folder named after the mod.

3. Find the game folder

In Steam (Desktop Mode), right-click the game, choose Manage, then Browse local files. Dolphin opens the game's install folder. For games on the internal drive, that's:

~/.local/share/Steam/steamapps/common/GAME NAME/

For games on a microSD card, the card is mounted under /run/media/. Depending on your SteamOS version, that's something like /run/media/mmcblk0p1/ or /run/media/deck/CARD NAME/. The games are in that card's steamapps/common folder.

.local is a hidden folder. In Dolphin, press Ctrl + H to show hidden files.

4. Proton games: the Windows-style folders

Windows games run on the Deck through Proton, and each one gets its own fake Windows drive (a "prefix"). Some mods, like save edits or config files, go into that game's Documents or AppData folder instead of the install folder. That folder lives under:

~/.local/share/Steam/steamapps/compatdata/APP ID/pfx/drive_c/users/steamuser/

The APP ID is the number in the game's Steam store address. For example, store.steampowered.com/app/489830/. The prefix only exists after you've launched the game at least once.

5. Watch the folder casing

This is the most common reason a mod "does nothing" on Steam Deck. Windows ignores upper and lower case in folder names. Linux doesn't. A mod made on Windows might contain data/textures while your game has Data/Textures. If you copy it as-is, you get a second data folder next to the real one, and the game never reads it.

Before copying, rename the mod's folders to match the game's folders exactly, one level at a time. Or use a tool that matches folders regardless of case (see below).

6. Mods that need a DLL loader

If the mod includes a file like dinput8.dll that goes next to the game's .exe, Proton will ignore it unless you tell it to load it. In Steam, open the game's Properties. Under Launch options, enter:

WINEDLLOVERRIDES="dinput8=n,b" %command%

Use the DLL's own name in place of dinput8. Separate several names with a semicolon (for example, dinput8=n,b;winmm=n,b). Remove the launch option to go back to normal. Where mods go lists the right name for BepInEx, MelonLoader, Script Hook V and other loaders.

7. Back up, then copy

Copy every folder the mod will change somewhere safe first, like a folder in your home directory. Then copy the mod's folders into the game folder. Dolphin will ask what to do about files that already exist: choose Overwrite, and tick "Apply to all" if you're sure.

Then return to Gaming Mode, launch the game and check the mod.

Undoing a mod

If you kept a backup, copy it back over the game folder. In Steam, Properties, then Installed Files, then Verify integrity of game files restores any game file the mod replaced. It doesn't remove files the mod added, though, so loaders and extra folders can stay behind. Delete those by hand, or reinstall the game for a fully clean start.

The easier way: BulkFileReplace

BulkFileReplace runs on Steam Deck as a Linux app (AppImage) in Desktop Mode, and it handles steps 5 and 7 for you:

• It matches folders regardless of case, so data/textures lands in your existing Data/Textures.
• It shows every change before anything is copied: which files will be replaced, which are new, and side-by-side previews of images, DDS textures and text.
• It backs up every original automatically, and one click undoes the whole install, including the files it added.

1. Download the AppImage in Desktop Mode.
2. Make it executable: right-click it, then Properties, then Permissions, then tick "Is executable".
3. Open it, drop in the mod, pick the game folder, check the changes, then Apply.

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