The 404 page now shows MMO Asteroids. After the game came out last year, I forked it to create MMO Spacewar (http://www.mmospacewar.com) where the rules were adjusted to be more like the iconic game (user now has a single life but also an energy bar, new warp command, and movement, shooting and getting hit costs energy but you regain energy over time) and additional improvements were made (you cannot get killed right after spawning, fixed sound effects, and users can choose the instance via a hashtag URL.)

The fork also lets you create asteroids and spaceships (added back from the original one-player version of the game), although at the moment they are not shared among clients so other players may be confused at what you're shooting at or is killing you.

One interesting aspect of this is that while developing I originally had my client playing on the MMO Asteroids Firebase table which in effect made this a cheat client (it can warp, not instantly killed). But it is a slightly more ethical cheat client in that the player still can be killed, the total amount of mobility is limited, and you only get one ship so instead of pure cheating it is like adding another spaceship class to MMO Asteroids.

Edit: I didn't have a lot of people to playtest with, so I'm not sure how much fun this actually is. My early observation is that it might be too hard to kill people and that you tend to have the best luck if your opponent moves around a bunch to deplete their energy.