Run the Editor (Proton)

1. Install s&box normally via Steam
2. .NET is not installed inside the editor’s Proton prefix by default, so you will need to install it yourself or run this Python script, written by Doctor Law, that installs it for you:

#!/usr/bin/env python3
"""Set up .NET 10 and Wine configuration for s&box in its Proton prefix."""

import os
import re
import shlex
import shutil
import subprocess
import sys
from pathlib import Path

APP_ID = "2129370"
DOTNET_DOWNLOAD_PAGE = "https://dotnet.microsoft.com/en-us/download/dotnet/10.0"

# Candidate Steam root directories in order of preference
STEAM_ROOTS = [
    Path.home() / ".steam/steam",
    Path.home() / ".local/share/Steam",
    Path.home() / "snap/steam/common/.local/share/Steam",
    Path.home() / ".var/app/com.valvesoftware.Steam/.local/share/Steam",
]


def die(msg):
    print(f"error: {msg}", file=sys.stderr)
    sys.exit(1)


def install_protontricks():
    mgr = next((shutil.which(t) for t in ("pipx", "pip3", "pip") if shutil.which(t)), None)
    if not mgr:
        die("protontricks not found and no pip/pipx available to install it.\n"
            "Install manually: https://github.com/Matoking/protontricks")
    print(f"Installing protontricks via {Path(mgr).name}...")
    subprocess.run([mgr, "install", "protontricks"], check=True)
    if not shutil.which("protontricks"):
        die("protontricks installed but not on PATH — ensure ~/.local/bin is in PATH and re-run.")


def check_deps():
    if not shutil.which("wine"):
        die("'wine' is not installed or not in PATH")

    pt = shutil.which("protontricks")
    if not pt:
        answer = input("protontricks not found. Install it now? [y/N] ").strip().lower()
        if answer == "y":
            install_protontricks()
        else:
            die("protontricks is required — install it and re-run.")
        pt = shutil.which("protontricks")

    if pt and pt.startswith("/usr/bin"):
        print("warning: system-packaged protontricks detected (apt version is often outdated).")
        print("         Run: pipx install protontricks  to get a current version.")
        print()


def steam_library_paths():
    """Return all Steam library 'common' folders found on this machine."""
    roots = [r for r in STEAM_ROOTS if r.is_dir()]
    if not roots:
        die("Could not find a Steam installation. Checked:\n" +
            "\n".join(f"  {r}" for r in STEAM_ROOTS))

    libraries = set()
    for root in roots:
        vdf = root / "steamapps/libraryfolders.vdf"
        if vdf.is_file():
            for path in re.findall(r'"path"\s+"([^"]+)"', vdf.read_text()):
                common = Path(path) / "steamapps/common"
                if common.is_dir():
                    libraries.add(common)
        # Always include the root's own library even if vdf is missing/empty
        default = root / "steamapps/common"
        if default.is_dir():
            libraries.add(default)

    return libraries


def find_installer():
    for common in steam_library_paths():
        matches = sorted(common.glob("**/dotnet-runtime-10*-win-x64.exe"))
        if matches:
            return matches[0]
    return None


def main():
    check_deps()

    installer = find_installer()
    if installer is None:
        print("No .NET 10 Windows runtime installer found in any Steam library.")
        print(f"Download the Windows x64 runtime installer from:\n  {DOTNET_DOWNLOAD_PAGE}")
        print("Place it anywhere inside a Steam library folder and re-run.")
        sys.exit(1)

    print(f"Installer: {installer}")
    print(f"Configuring Proton prefix for s&box (App ID {APP_ID})...")

    quoted = shlex.quote(str(installer))
    wine_cmd = " && ".join([
        f"wine {quoted} /install /quiet /norestart",
        r"wine reg add 'HKEY_CURRENT_USER\Software\Wine\X11 Driver' /v Decorated /t REG_SZ /d N /f",
        r"wine reg add 'HKEY_CURRENT_USER\Control Panel\Desktop' /v FontSmoothing /t REG_SZ /d 2 /f",
        r"wine reg add 'HKEY_CURRENT_USER\Control Panel\Desktop' /v FontSmoothingType /t REG_DWORD /d 2 /f",
        r"wine reg add 'HKCU\Software\Wine\DllOverrides' /v comdlg32 /d native /f",
    ])

    env = {**os.environ, "STEAM_RUNTIME": "0"}
    result = subprocess.run(["protontricks", "-c", wine_cmd, APP_ID], stderr=subprocess.PIPE, text=True, env=env)
    if result.returncode != 0:
        if "Invalid file magic number" in (result.stderr or ""):
            die("protontricks failed: appinfo.vdf format not supported by this version.\n"
                "Upgrade with: pipx install protontricks")
        if result.stderr:
            print(result.stderr, file=sys.stderr, end="")
        die(f"protontricks exited with code {result.returncode}")

    print("Done.")


if __name__ == "__main__":
    main()

3. Right click s&box editor in your library > Properties… > Compatibility > Check “Force the use of a specific Steam Play compatibility tool” > Select “Proton 11.0 (Beta)” or newer

4. Add PROTON_SET_GAME_DRIVE=0 environment variable to s&box editor’s launch options

5. Run