From Impulse you can see the list of matches that are currently running, would be a great idea (mostly for tournaments) to be able to join them in "Spectator Mode"... this means that the server will forward to the spectator all the packets for display what is running on (in this way there will not even be load on the players so no lag caused by spectators).

Of course, with such design, you will need an impulse server(s) that will forward the packets to the spectators but well, i hope you have already a server that receives the packets and validates them (for preventing cheating) of actual games. (didnt tested yet to try alter packets during a game session)