For those who can't access it: It uses an emulator written in javascript that has been modified. It runs the entire pokemon red game as normal but layers on other users allowing you to play them, using ram hacks to force the game AI you are actually playing to be identical to the person who you want to play with. If you log in to facebook it will let you play exclusively with your fb friends. It was made at PennApps, I happened to have seen one of the people on their team saying he was sure their server could take the load they might get, turns out he was pretty wrong.
Glancing at the chromium developers console, there's a javascript not loading because nginx is returning that error for the jsgb.firecaster.com domain, but it loads fine for the plain firecaster.com domain.
It may just be a configuration error in nginx. So, if they fix that, they may be running again.