In Steam, go to Games > Add a Non-Steam Game to My Library , browse to CoJGunslinger.exe , and add it. Launching from within Steam often bypasses the error because Steam is explicitly running.
If you launch the game and Steam is not installed or not running, the executable throws the error and closes. This is particularly common after using a cracked or modified executable from a non-Steam source, or when the game was installed via a disk that assumed Steam would be present. Fortunately, resolving this does not require advanced hacking. There are several reliable solutions. In Steam, go to Games > Add a
If you have no moral or technical objection to Steam, simply install it, create a free account, and leave it running in the background. Launch the game. Even if the game was purchased elsewhere, the Steam client’s presence satisfies the check. You do not need to buy the game again on Steam. This is particularly common after using a cracked
The most elegant solution is to replace the game’s launcher with a version that removes the Steam requirement. Reputable sources like PCGamingWiki provide official patches or links to modified executables (often from the GOG version, which eventually released a truly Steam-free build). After backing up the original .exe , replace it with the patched one. The game will then launch directly. If you have no moral or technical objection