So I made it to wave 53 at my first try, very nice little game.
Not so much content but the game works fine, I love the visual of the units and the variety of it.
I feel like you should try to make both players and ennemy a little bit smaller maybe like 80% of there size. I wish we could upgrade our ship or unlock new slots for weapons with the coins we get by boss.
You should really add borders to the size of the screen because right now you can just fly far away and avoid shoots by going off-screen :)
Also a nice space-music could be very good for the game, and another more epic for the boss levels. There are many free music online for you to get and it can make your game much better !
Nice overall game :)