How to download games for Steam for another platform?

Solution 1:

Valve's SteamCMD does just that. A short and incomplete transcript:

1. Download and unpack steamcmd.
2. Install 32-bit compatibility libs: sudo apt-get install lib32gcc1
3. Login in the command line: ./steamcmd.sh +@sSteamCmdForcePlatformType windows.
4. In the steamcmd:
5. login <username>
6. force_install_dir <path>
7. Find the app id of the game (it can be found in the game's store page URL: http://store.steampowered.com/app/<app_id>).
8. Download the game: app_update <app_id>

Solution 2:

Steam can also be tricked into downloading games that are unavailable on your platform.

To manually download the app whose id is $APPID into $INSTALLDIR, create the file named appmanifest_$APPID.acf in your steamapps folder¹ with the following contents:

"AppState"
{
  "AppID"  "$APPID"
  "Universe" "1"
  "installdir" "$INSTALLDIR"
  "StateFlags" "1026"
}

More information is available at the above link. Other solutions are possible, like using Lutris to manage your game library.

¹ Default location:

• ~/.steam/steam/SteamApps on Linux
• ~/Library/Application Support/Steam/steamapps on macOS