Issue Description: You installed Sphere3 via the Sphere3-66-pr.exe launcher as a non-Steam game within Steam using Proton. Upon initial launch, the game opens the Sphere3 website, prompting you to download the game. After clicking the Play button on their site, the game launches successfully without any issues. However, after exiting and attempting to re-launch the game, the client returns to the website with the Play button, rather than recognizing the game as installed locally.

Possible Causes and Solutions: Proton Compatibility:

The behavior you're experiencing could be related to how Proton interacts with certain game launchers or installers. The launcher may not be fully registering the game as installed due to Proton’s handling of the Windows executable. Solution: Consider using an alternative Proton version, such as Proton GE (GloriousEggroll), which is a community-supported build known for offering enhanced compatibility with certain games and launchers. You can switch to Proton GE by selecting it in Steam's compatibility settings for the game.

Launcher Initialization:

It's possible that the Sphere3 launcher relies on external communication (e.g., checking game files or performing updates) after the first launch. If Proton isn’t allowing the launcher to save its data locally or if permissions are misconfigured, the launcher may fail to recognize that the game has been installed. Solution: Ensure that Proton has the proper file permissions to read and write data in the game’s installation directory. Additionally, check for any configuration files or cache folders within the game’s directory that could be used by the launcher. You might also want to try enabling the "Run this game in a virtual desktop" option in Steam’s Proton settings to see if it improves the launcher’s behavior.

Steam File Integrity:

Since you're using Proton to run the game, Steam may not recognize the game as properly installed. This can result in the launcher redirecting to the website each time it’s launched. Solution: Right-click on the non-Steam game in your Steam Library, select Properties, and check if there are any options to validate the installation. Though Proton is being used, Steam may still allow you to verify the integrity of the files to ensure everything is set up correctly.

File Permissions and Logs:

The issue could also be related to file permissions or improper handling of data by Proton. Checking the logs could help identify specific errors that are c