Like it was said before, would be interesting to see it used in an actual game - except, it gets laggy after enough strokes (not surprisingly, of course), so it might be a challenge!

It could use a "start again" option so one wouldn't have to reload the page. Also a "pause and draw" would be helpful.

And some colours...

I do like that each "stroke" basically turns into one plane and when you wait a moment and add some more stars it's like another plane at an angle. And if you do it right, you can get an effect that - although the simulation turns linearly all the time - some parts appear to stop while others continue their rotation (and sometimes even seemingly speed up).

It would be fun to be able to spin the camera a bit and see the depth a bit more, but otherwise seems neat. Would interesting to see how you plan to use this in a game.