Nice idea, but old tactic still works: Never stop and drive circles or at bosses: left / right. Never died, because (sorry to say), the KI is damn stupid. Wished, there were more useful upgrades, more levels and more different enemies. The only thing that differs from level to level: The bosses, but also not that much. The last boss was nice, because a bit harder than the others ones (homing missiles). But besides this all, it was a nice time & i won't regret any minute, spent on your game!