Many emulators have this functionality, called netplay. For example Mesen, one of the best NES emulators available: https://www.mesen.ca/docs/tools.html#netpla

Many emulators have this functionality, called netplay. For example Mesen, one of the best NES emulators available: https://www.mesen.ca/docs/tools.html#netplay https://www.mesen.ca/docs/tools.html#netplay Also RetroArch (which has cores for many systems, including Genesis): https://www.retroarch.com/index.php?page=netplay https://www.retroarch.com/index.php?page=netplay