A lunar defence game I made using flash AS2.0 (I don't like AS3). It's a really basic arcade game in which you defend the moon from asteroids that threaten to destroy it's colonies.
Use your cannon, railgun and overshield to protect the colonies. Upgrade your weapons, decrease their cooldowns, increase their blast radius etc in the upgrade screen.
Enjoy! (don't forget to read the instructions, it's only 3 lines!)
Small tip: For those of you who find it too hard in the beginning; The CANNON timer resets every time you hit an asteroid, so by aiming well in the beginning you can kill a lot more asteroids even WITH the long cooldown. Also upgrades become very powerful later on and you have A LOT of health (3x100) in the beginning so you should be fine!
EDIT: Added pause when buying upgrades. Reducing cooldowns isn't nessecary, tested it extensively, game starts off a bit slow though.