Great idea, great execution.
It's a fairly novel idea, using enemy ships against themselves while maintaining your own life bar. The difficulty is spot on, making it just hard enough to be challenging, yet the gameplay is very fair and forgiving of mistakes. The geometry-based collision detection was noticed AND very welcome, as it allowed me to pilot the tiny ships through tiny gaps (ala shmups) when I needed some recovery time, though I preferred the standard ship for its durability. But perhaps the best part of the game was infecting the shielded gunship. It has a wicked lifebar and offensive power, but is offset by its size, slowness, and low RoF. The most fun I had in the game was nervously keeping my gunship alive, silently cheering when a bullet grazed just over the front curve without colliding. It truly felt like a real shmup game compared to the others I've played on Newgrounds.