My first shoot-em-up. You have 3 lives. Get 100 points to win. Space to shoot, b to use a homing missile. Not much else to say here.
Sound effects come from the scratch dev team Music from the wonderful Kevin Mcleod who gives away music for free like a magical wizard: http://incompetech.com If it shows the Game over screen when you press the flag, press it again and it will fix it.