I haven't listened in on the data but it seems likely that MIDI Maze only uses the electrical standards, i.e. a proprietary protocol over MIDI ports

It's a midi port. It does midi. Hence the limit of 16 players. Every player is using a dedicated midi channel.

I agree that it's a MIDI port. That's not under contest.

Because every claim that it's MIDI I've seen has failed to substantiate it, I searched around a bit today and found the developer of MIDI-Maze II and contacted him. Only the physical layer of MIDI is used. He furthermore said that MIDI doesn't allow a ring network anyway, in which case this must also be true for the first MIDI-Maze.

So no, the player limit has nothing to do with MIDI channels. Maybe be more clear about whether what you're saying is an unsubstantiated guess or something that you actually know. Your message reads a lot like you know it for a fact.

I stand corrected then I guess. I definitely read before that it uses plain midi messages.