This is pretty fun. For 5 minutes atleast.
But after that it gets monotonous, with very little to do but try and get some achievements.
It's a bit laggy and that makes it frustrating especially if you click outside by mistake when the enemies are near the right edge of the screen.
You could have added a shop where you can buy stuff to modify your weapon.
Also, I think the 30,000 medal is for the base score not the final score, because I got a final score of 42,000 after adding bonuses and still didn't get it.
All in all, a good game. Make a better version next time and you'll get the remaining half star as well.