Defeat wave after wave of invading alien ships while dodging frantically between barriers of various shapes and sizes, some stationary, some mobile. Play endlessly in �Practice� mode, with no limit to the number of times you can be killed, or see how long you can survive with 6 lives (�Normal� mode) or a meager 3 lives (�Hard� mode).

Use the left and right arrow keys to move. Your ship will fire automatically. In Practice mode, press Q if you want to return to the title to change difficulty levels. There are 15 waves per loop� and as many loops as you can survive.