For certain games, like Black Ops II , Steam's overlay or background processes can interfere with how Nucleus Co-op identifies the game window.
The OpenNet plugin is a designed to simulate a local area network (LAN) for games that do not natively support split-screen on PC. When you see the "Unknown Process" alert, it means the software has successfully launched the game's executable, but the internal "hooks" needed to manage separate controllers or network IDs have attached to a process ID that doesn't match the expected game profile. Primary Causes and Solutions 1. Outdated Game Scripts Opennet Plugin Loaded Into An Unknown Process
If you are playing a game with multiple .exe files (e.g., a launcher vs. the actual game), the plugin might attach to the launcher, which then becomes an "unknown process" once it closes to start the game. For certain games, like Black Ops II ,
Ensure the OpenNet.dll file hasn't been quarantined by Windows Defender . Primary Causes and Solutions 1
Most Nucleus Co-op errors stem from a mismatch between the game version and the script handling it.
Repair corrupted .dll or .exe files using the Steam Verify Integrity tool.
High display scaling (above 100%) or mismatched resolutions can cause the plugin to fail during the window-hooking phase. Set your Windows "Scale and Layout" to 100% .