I thought something similar, but it said "swap" so I was wondering what we were swapping, and I thought "I give you a commandline window onto my box, and you give me a commandline window onto your box, and we see who can create more mischief/mayhem most quickly"
but then I came up with a cool "network war" game: there's a shared window on our two boxes over the net (one window on your box, one window on my box) but inside the window are bash cmdlines for both of our boxes. Whatever commands you type get executed on both machines; whatever commands I type get executed by both shells too... stdout outputs are intermingled? atomic interspersed? it should be confusing but not impossibly so
Hmm... You can run different CTF environments i to a VM, wouldnt take much to stream input back and forth to both machines. I just saw another item featured on HN for piped keyboard streams between multiple users on the same shell.