I am very impressed with the soundwave shaders and really all visual aspects of the game. As other commenters mentioned, my only problem with the game was the aiming, and either switching around the controls for that or unhiding the mouse cursor would do wonders for the game. You've got a good base for a good game here. I know that with more time you'll be able to flesh out the controls, add some more enemies, levels, and some more mechanics (the sonar grenade you mentioned sounds like it would be really cool)