SMAPI/build/find-game-folder.targets

<Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
  <!-- import developer's custom path (if any) -->
  <Import Condition="$(OS) != 'Windows_NT' AND Exists('$(HOME)\stardewvalley.targets')" Project="$(HOME)\stardewvalley.targets" />
  <Import Condition="$(OS) == 'Windows_NT' AND Exists('$(USERPROFILE)\stardewvalley.targets')" Project="$(USERPROFILE)\stardewvalley.targets" />

  <!-- find game path -->
  <Choose>
    <When Condition="$(OS) == 'Unix' OR $(OS) == 'OSX'">
      <PropertyGroup>
        <!-- Linux -->
        <GamePath Condition="!Exists('$(GamePath)')">$(HOME)/GOG Games/Stardew Valley/game</GamePath>
        <GamePath Condition="!Exists('$(GamePath)')">$(HOME)/.steam/steam/steamapps/common/Stardew Valley</GamePath>
        <GamePath Condition="!Exists('$(GamePath)')">$(HOME)/.local/share/Steam/steamapps/common/Stardew Valley</GamePath>
        <GamePath Condition="!Exists('$(GamePath)')">$(HOME)/.var/app/com.valvesoftware.Steam/data/Steam/steamapps/common/Stardew Valley</GamePath>

        <!-- macOS (may be 'Unix' or 'OSX') -->
        <GamePath Condition="!Exists('$(GamePath)')">/Applications/Stardew Valley.app/Contents/MacOS</GamePath>
        <GamePath Condition="!Exists('$(GamePath)')">$(HOME)/Library/Application Support/Steam/steamapps/common/Stardew Valley/Contents/MacOS</GamePath>
      </PropertyGroup>
    </When>
    <When Condition="$(OS) == 'Windows_NT'">
      <PropertyGroup>
        <!-- registry paths -->
        <GamePath Condition="!Exists('$(GamePath)')">$([MSBuild]::GetRegistryValueFromView('HKEY_LOCAL_MACHINE\SOFTWARE\GOG.com\Games\1453375253', 'PATH', null, RegistryView.Registry32))</GamePath>
        <GamePath Condition="!Exists('$(GamePath)')">$([MSBuild]::GetRegistryValueFromView('HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\Steam App 413150', 'InstallLocation', null, RegistryView.Registry64, RegistryView.Registry32))</GamePath>

        <!-- derive from Steam library path -->
        <_SteamLibraryPath>$([MSBuild]::GetRegistryValueFromView('HKEY_CURRENT_USER\SOFTWARE\Valve\Steam', 'SteamPath', null, RegistryView.Registry32))</_SteamLibraryPath>
        <GamePath Condition="!Exists('$(GamePath)') AND '$(_SteamLibraryPath)' != ''">$(_SteamLibraryPath)\steamapps\common\Stardew Valley</GamePath>

        <!-- default paths -->
        <GamePath Condition="!Exists('$(GamePath)')">C:\Program Files\GalaxyClient\Games\Stardew Valley</GamePath>
        <GamePath Condition="!Exists('$(GamePath)')">C:\Program Files\GOG Galaxy\Games\Stardew Valley</GamePath>
        <GamePath Condition="!Exists('$(GamePath)')">C:\Program Files\GOG Games\Stardew Valley</GamePath>
        <GamePath Condition="!Exists('$(GamePath)')">C:\Program Files\Steam\steamapps\common\Stardew Valley</GamePath>

        <GamePath Condition="!Exists('$(GamePath)')">C:\Program Files (x86)\GalaxyClient\Games\Stardew Valley</GamePath>
        <GamePath Condition="!Exists('$(GamePath)')">C:\Program Files (x86)\GOG Galaxy\Games\Stardew Valley</GamePath>
        <GamePath Condition="!Exists('$(GamePath)')">C:\Program Files (x86)\GOG Games\Stardew Valley</GamePath>
        <GamePath Condition="!Exists('$(GamePath)')">C:\Program Files (x86)\Steam\steamapps\common\Stardew Valley</GamePath>
      </PropertyGroup>
    </When>
  </Choose>
</Project>