...
Well for starters, you kinda spelled defense wrong.
This game is just another one of the unoriginal "revolving turret don't let anything touch you" kind of games... not much effort was made to differentiate this game from the others.
The turret animation and design is really good, its just a shame it was put to bad use. I like the ammo switching thing and and the upgrades weren't terrible... but really... you could have had a lot more going with this.