Nice try.
Well, it's just your basic shooter, and classical, just take down the aliens and don't die. Classical, always work. Now let's review it technically.
First, no sound effects, it's a downside, but meh. The music you chose gets annoying after a while although I'm quite sure your game wasn't intended either to be played for 2 hours straight. But at least, it was fluid, it was easy to play (I saw some flash games that actually had complicated settings...). I just don't understand the point of the first-ship trap.
Overall, well... it's pretty poor in content, but I'm pleased to see this flash breathes fluidity. At least you have this on your side. Keep it up, and good luck for your next works.