Test which source carries the sound
Play game audio while you are silent. Mute the named microphone source in OBS. If the game remains, it is also reaching OBS through another source. If it disappears, inspect the microphone device or mix selected for that source.
Turn off speakers and listen through headphones. If the microphone now stops picking up the game, reduce the acoustic leakage or keep headphones. A noise gate cannot separate game sound from your voice while both are present.
Separate a microphone from a complete mix
Check whether the OBS source selects a physical microphone or a virtual stream mix. A stream mix can intentionally contain game audio. Do not capture it together with another full copy of the same game sound.
Use the audio routing builder to decide whether OBS receives individual sources or a finished mix. Check mute and monitor behaviour on the chosen path before adding filters.
Record voice and game separately
Record a silent passage with game sound, then speech with the game still playing. Listen for a duplicated or delayed game signal. If it remains in a Wave Link route, use the Wave Link double-audio checks.