Super addictive gameplay
There's something about this game that just makes you wanna come back for more each and every time. Maybe it stems from the simplicity of the game's concept, and that it remains faithful to that which all GOOD arcade games are: gameplay.
Awesome graphics and sound. Your style reminds me slightly of the Robotech mechs.
And on a sidenote, my score was 47319 on level 12 :D.