Good basics, but nothing more.
The core of this game is mostly well done, but in such a saturated genre as the top-down flash shooter, there's nothing else aside from that to get anything higher than the score I gave it. It's smooth, the weapons are accurate, the animation was nice. But...
The story is non-existent save a few scenes at the very start to give a setting. I'm a sucker for a good story, but there's not even an attempt at one here. While I do have to congratulate you on using a female character who isn't overly sexualized just for the sake of... there's nothing interesting about her. No name, no voice, no personality... just a place holder. An interesting story, a solid character, with these things you could really pull your work above the rest. It can entertain the reader that much more if they are invested in what's going on aside from some time killing.
I found almost zero challenge to the game. Some of the enemies were on the verge of being a nuisance, but just by spamming the earliest unlocked weapon you can keep alive. It was almost boring through the entirety, and being rewarded with very little aside from new guns that wasn't really needed, and eventually at the end some medals didn't spur me on to play further. Some better form of rewards, like more creative medals, different difficulty settings, unlocks... these can all help the player want to keep moving.
Also, why is this game rated M? I've seen E rated games that are worse than this. There's no sex, no strong language, and the violence isn't bloody in the least. It's somewhat misleading.