Hey HN,
My friends and I made this the other day. It is 100% javascript using node.js and canvas.
When you call in, you connect to Twilio's server, which does a request to our server, which then sends a message down to the browser using socket.io, and then your tanks shoots.
That means your signal is going from your phone, to the cell tower, INTO SPACE, back down to california, and then travels over the internet to reach you at your computer.
The latency should be less than 1s, which is pretty impressive considering how far the signal travels.
I hope you guys enjoy, make sure to have a friend play with you.
Also, it uses an 888 number so it should be toll free :)
Cheers,
David, Paul, and Justin