This is one of the better shooters on Newgrounds. The mix of weapons and enemy types makes the gameplay strategic enough to be quite fun and the building/upgrade system is great. This game offers a shooter with just the right amount of tweaking; the offerings manage to avoid adding much complexity to the controls while still offering an interesting level of tactics. This isn't the first game I've encountered that required the player to protect the bottom of their screen, but it's definitely one of the best of them.
A well-executed, fun game.