Needs a bit of work
When i first started, i thought that it would shape up to be pretty fun.
But as i progressed through the game (if you can call it that), it started to get boring.
First off, there are way to many side scrolling survival games in the world now, and not many of them are very unique. You should try to make things a little different next time.
Mabye instead of powerups simply increasing the rate of fire on your weapon, it could make different things fire from it, or how many things fire at once. The fire rate powerups made the game insanely easier as the game went on, even though more ships started to flood in. All you had to do was hold down left click and it would just send a straight continueous chain of bullets that blew up anything it touched. Im not saying you should have an upgrade menu where you bought stuff, but something a little different
And mabye you should include bosses and different enemies that took more than one shot to destroy.
Even though it was alright, but it wasnt unique enough to make it stand out from the crowd