It's been quite some time since I first made the source code to A Robot Named Fight! available to the public, but it's finally bore fruit!
Discord user Ettokun has created a mod for the game that enables online co-op! You can find out everything about it here: https://github.com/Renevark/arnf-netcoop/releases
To be perfectly clear, this isn't just orb co-op, but full, two Fights, online co-op.
Ettokun has release multiple patches and improvements since making the mod available to the public several days ago. To stay in the loop, join the MGS discord here: https://discord.gg/fj7zqJvzm