I really love the "paper draw" art style! It is awesome! Also the animations are perfect with the art style (love the background animation as "pen colouring").
For a ten days dev there are a lot of variety!! The bosses are different, both in projectile patterns and artistically speaking (fat Godzilla and humanity tank are my favourites!)
The gameplay is very fun, I preferred boss rush but is my personal taste (like bosses rush in general).
The main mode is a bit chaotic but that's the beauty of it!
I liked the tutorial, although I thought it was sometimes difficult to read (maybe a white border to the font would be enough I think).
Overall is an awesome and fun game to play. I really liked it!
Thanks for create and sharing it!
P.s I love those stick figure men on the ground :D
And I hate all those people who start skydiving during an alien invasion! :P