As workaround you should use one of methods at Unsupported Games. And if you want to see it officially at Mudfish, please send us some game packets using Packet Capture with Mudfish link while playing the game with Full VPN mode. We need some game packets to register new game server.

it is an emulator for old arcade games to play online, it works with p2p (i think) but i think it sends packets somewhere to a server when you host a match so you can play p2p (since i can play online with full vpn mode and not without it), knowing this i can still do the packet capture with mudfish so you can add fightcade to mudfish?

If your game is based on P2P, Mudfish could not be helpful to play the game because there are limitations https://docs.mudfish.net/en/docs/mudfish-troubleshooting/p2p-based-games/