Just pointers, amigo...
OK. Not bad. Better than anything I've ever done, but...
Make everything slightly more detailed AND smaller. A difficult task, but it can be done. The screen looks far too crowded. Also, add street thugs, soldiers, or police that can also shoot at the copter.
Finally, the MAJOR annoyance: once the 'scientist' warns us of the approaching tank, take the message off-screen within 15-20 seconds. You can't shoot through it and the screen is limited enough already.
Just my $.02