space war from webrtc for the curious

What things did you imagine being built with RTP? Do have any cool RTP projects/ideas that got lost to time? #
One of the fun things I built was a version of the classic “Spacewar” game which used IP multicast. Without having any kind of central server, multiple clients could each run the spacewar binary and start broadcasting their ship’s location, velocity, the direction it was facing, and similar information for any “bullets” it had fired, and all of the other instances would pick up that information and render it locally, allowing users to all see each other’s ships and bullets, with ships “exploding” if they crashed into each other or bullets hit them. I even made the “debris” from the explosion a live object that could take out other ships, sometimes leading to fun chain reactions!

In the spirit of the original game, I rendered it using simulated vector graphics, so you could do things like zooming your view in & out and everything would scale up/down. The ships themselves were a bunch of line segments in vector form that I had some of my colleagues at PARC helped me to design, so everyone’s ship had a unique look to it.

Basically, anything that could benefit from a real-time data stream that didn’t need perfect in-order delivery could benefit from RTP. So, in addition to audio & video we could build things like a shared whiteboard. Even file transfers could benefit from RTP, especially in conjunction with IP multicast.

Imagine something like BitTorrent but where you didn’t need all the data going point-to-point between peers. The original seeder could send a multicast stream to all of the leeches at once, and any packet losses along the way could be quickly cleaned up by a retransmission from any peer that successfully received the data. You could even scope your retransmission requests so that some peer nearby delivered the copy of the data, and that too could be multicast to others in that region, since a packet loss in the middle of the network would tend to mean a bunch of clients downstream of that point all missed the same data.