Why not data-stream the hex used by a player to the server and distribute it to all other players, and make the players only send their key strokes (i know, when the game uses random values it will stuff up the hole thing), but maybe also upload the mem-spaces?
:'( sorry if you think my idea is crap :(
This will never work, sadly. As far as I am aware, the maximum amount of data that can be sent in a console command is 253 bytes if you use a single character for the command. On top of that, you need to encode special characters, which will further reduce how much you can send per command, and there is also likely a limit to how many console commands you can send per second.
Combine that with the fact that order matters, so you need to send an index value also, further reducing how much you can send.
A lot of roms are between 65,536 and 262,144 bytes in size - assuming console command always arrive in the order you send them always ( so you could drop the index value ), you still have the issue of it taking hundreds of console commands to run.
So it would be EXTREMELY slow using standard Lua and wouldn't work out very well.
Then comes the copyright issues - distributing the roms is a copyright infringement as well as downloading them.