fwiw, I love coffeescript. I write a game a few weeks ago in it, but I've never shown it to anyone before. Have a look here if you're interested http://quietcode.com/vectroid
I've made no attempts at all at performance tuning yet it runs very nicely in webkit browsers and not too bad in firefox.
Wave 7 - 327950, no deaths, got bored and quit first try. It's too easy! You should add difficulty levels. (I played a lot of Touhou recently so my sense of "difficult" is in a non-standard location.) Also, more enemies that shoot things that can't be destroyed, and enemies/asteroids that need multiple hits to die (maybe enemy health increases for higher difficulty / later waves).
Bugs I noticed: All the bullets in the world sometimes disappear at once. There's no pause button.
Mostly I love the controls, except friction on your ship is a little aggressive -- I think there should be no friction if you're below a certain speed, but maybe it's just my expectations from Star Control 2 (check out the FOSS version, Ur-quan Masters, with sudo apt-get install uqm if you're on an Ubuntu-like system). Also, the game desperately needs a hold-to-fire, or even toggle fire, button. Single-shot fire in a game like this is why there was a thriving turbo controller cottage industry in the '80s - '90s.
Yes, I was trying to reward the player for flying faster instead of just sitting on one spot. Projectile speed increases as your speed increases. I though damaging your own ship would just be cruel :)
You may also notice the view zooms out as your speed increases, so you have a much wider view
The stars in the background are awesome! I think it's a little hard to see your projectiles though against the background, maybe make them a little thicker?
Yes, it's a bit hard to see but I haven't really spent any time tuning it - been too busy. Did you nitice the little blue ships that you can shoot to get a token to upgrade your guns? There's red ships that follow you that show up every 30 seconds, and blue ones that contain powerups that show up after (I think) 10k points.
Real time (and spacebar) killer! Got to 257000 points before making myself stop. A few gameplay adjustments and multiplayer, and I bet I'd lose a whole evening to it.
The code appears to be very well-structured and readable, even though it's compiled to JavaScript. IMO, a good example for those learning to use canvas (like myself). Thanks a lot for sharing.
I've made no attempts at all at performance tuning yet it runs very nicely in webkit browsers and not too bad in firefox.