as represented by the hearts shown in the upper left. You die if your energy bar reaches zero or if you get shot by an alien.Each time you start a level your energy meter is full.You beat a level whenever all the aliens on it are destroyed.This game has 10 levels which are unlocked sequentially.Your cumulative game score is shown in the upper right corner.An energy bar is shown across the top center.
Destroy them while avoiding their shots & beat the level before your energy meter runs out to retain all of your lives. Clear each stage of aliens to move onto the next stage.
