At the end of each level, the player is greeted by a friendly and heavily armed boss. It might take forever to kill it, so if the boss is not killed after a certain period of time, the game goes to the next level anyways. After the level is complete, the player is shown his score and the percent of the enemies eliminated. Several levels give access to secret levels, so keep your eyes open. In arcade mode, they can be picked up on the level.
Player can upgrade the ship, the shields, the generator, and the weapons.
The ships vary it looks, price, and amount of armor. The shields play a very important role in the game - they absorb hits without damaging the ship's armor. Several shields can be purchased, but more shields mean greater cost. The generators affect the rate at which the shields are restored and the energy drain from firing the weapons. Better and more expensive generators restore shields much faster, increasing the chances of surviving the level.