This is fun! I had to play the downloaded version instead but it really does the game justice as web lag quite a bit. The game is super enjoyable, the controls are fun and intuitive, and the movement is really the icing on the cake. It feels so good! Played till wave 8 and got overwhelmed by enemies but I guess I did an okay job.
For some criticism, I'd say the laser weapon is extremely good, and I don't see a reason not to use it. That's a problem because there is that satisfying machine gun you could use, but since it's not a hit scan weapon and it deals so little damage, I only use that on the boss when waiting for the laser to cool down. Heck, why even have ammo requirement for it? It's so underpowered already. Another issue I think si that it's a bit hard to understand how the shield works. The bullet sticks onto you even after the shield is up, and I resort to powering up the shield until the bullet disapeared, (and no sound effect or visual effect for that too), and feels like I am wasting shield energy too much. A minor thing too is the collectables needed too much wait before they were collected, and it really frustrates players like me who need that ammo/crystal quickly in a pinch.
Anyway, this is a very good game! Well done!