Don't need a weapon cooldown. Off-screen is enough, and more 'retro'. </hipster>
Slight increase of wheel upper bound.
Rudimentary enemy spawning via button press and traveling down the screen.
Alien movement is looks pretty much like I want it to.
Projectile+Alien collision detection+removal and score incrementing. No way to see the score yet...
Enemies kill you and reset the game by touching you.
Enemies spawn by chance which increases over time
Max enemies changed to 4
Scoreboard rendering!
Fixes build errors on the avr-gcc compiler I installed in Ubuntu 13.10.