Another Space Invaders HTML5 update. The only thing I did with this build was fix the speed increase. It dawned on my after watching video of the original that the speed increase was gradual, not that it picked up at specific numbers of Invaders remaining. Reading about it on Wikipedia, I learned that the original Invaders were actually constrained in speed by the hardware, and that as you destroyed more of them, the CPU had fewer things to do so took care of updating the remaining ones in the phalanx faster and faster.
I still have yet to implement the bunkers; it’s not straightforward to do destructible sprites, and I haven’t yet looked into methods for accomplishing it yet, but apart from fixing the high score glitch that’s all that’s left.
Oh, I suppose I could give extra lives after a certain number of points scored, if you insist.