There a little cheat/glitch
If you hold down the right mouse button and move the crosshairs off the screen while still holding down the button, you can let go of the right mouse button and the satellite will continue firing as if the button is still being pressed. Then you just move the crosshairs around until the wave ends and then click the screen again to disengage it so you can upgrade/buy weapons from the shop. Then at the start of the wave, repeat the first steps again. Makes the game a little too easy, especially when you have the side mounted rocket pods maxed out.
It's fun nut it seems to lack an addictive property. It's just to little action for to little reward. Like I said it's fun for a bit. It just dosen't quite hold my attention. I must say the music is fantastic though! I would simply make the enemies faster a from the start and make the kamikaze ,but also buff the gun at the start faster one shot kill until later rounds introduce the shooting units that take more than one hit.