Gamma Emerald is not released on Steam
Steam shortcuts are not a Steam release
Windows users can add almost any executable to their Steam library as a non-Steam game. That only creates a local launcher shortcut and optional controller overlay. It does not provide:
- Steam updates or cloud saves;
- a verified Steam Deck compatibility rating;
- support from Valve or the creator for Proton;
- an official store license or community hub.
Community reports about running the game through Proton or on handheld PCs are device-specific. The creator's documented target remains Windows 10/11 64-bit with desktop-style RAM and graphics requirements.