Sonic Adventure DX – Mod installation (Steam Deck, GUI only)

What you need

  • Protontricks – install it from the Discover store on the Deck (Flatpak is the recommended package).
  • SADX Mod Installer – the official Windows installer (sadx_setup.exe).
    Download it from the project page: https://gitlab.com/PiKeyAr/sadx-mod-installer

Preparation

  1. Launch the game once in Gaming mode and quit.
    This creates the Proton compatibility folder for the game (AppID 71250).

  2. Switch to Desktop mode (Steam → Power → “Switch to Desktop”).

Using Protontricks GUI to run the installer

  1. Open the File Manager and navigate to the folder where you saved sadx_setup.exe (usually ~/Downloads).

  2. Right‑click on sadx_setup.exe → “Open With Protontricks” → choose “Sonic Adventure DX (AppID 71250)” from the list.
    Protontricks will automatically pick the correct Proton prefix for the game01.

  3. The SADX Mod Installer window appears.
    • It detects the Steam installation path (…/steamapps/common/Sonic Adventure DX).
    • In Guide/Selection mode tick the mods you want. Typical “best‑experience” set:
      • Dreamcast Conversion (core graphics & models)0
      • BetterSADX / HD GUI (menu polish, controller support)4
      • Texture Upscale (xBRZ / ESRGAN) (higher‑res textures)3
      • Sound‑overhaul (optional music replacement)6
    • Click Install and wait while the installer patches the Steam executable, copies the selected mods into a mods sub‑folder, and writes a tiny configuration file.
  4. When the installer finishes, close it.

Back to Gaming mode & launch

  1. Click the Steam icon on the task‑bar → “Return to Gaming Mode.”

  2. In your library select Sonic Adventure DX → Play.
    You should now see the Dreamcast opening cinematic, up‑scaled textures, and any extra audio you chose.

Tweaking later (still GUI‑only)

  • To enable/disable individual mods, open the game folder (…/Sonic Adventure DX) in Desktop mode, right‑click SADXModManager.exe → “Open With Protontricks” → select the SADX AppID.
  • The Mod Manager UI lets you reorder, toggle, or configure each mod without leaving the GUI0.

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