Surprisingly fun and addictive. You have tuned all the moving parts nicely, such as shield width, projectile speed, fire rate, breathing pauses and all that. Very good use of limited time as it is scoped very well and time was put into the right aspects! Good work!
I would like a way to skip the tutorial, and the slower more scattered shots should give more score per bullet so that each type of wave will net you the same total amount of points, now it felt like "damnit, not the wave-attack, I will get fewer points for this".