Needs instructions! It took me a bit to figure out what kind of game this was, let alone what to do. It's a neat take on Missile Command though.
One of the first 2 or 3 blocks clicked should always have "code" in it so that you can have a chance to defend yourself. Twice I lost before I was able to find a code turret which was really frustrating.
The defense explosions seemed to miss an awful lot, even when completely enveloping the incoming fire.
My entry: Dead Drop