Comprising of 20 different challenge locations, there's 60 levels to fight through, so it's understandable that the player should have a helping hand from an array of extremely useful power-ups, including protective shields, additional support craft, rapid-fire shots and column-clearing laser beams – essential aides as the action becomes progressively more intense. Even better news is that these power-ups can be used in combination: using the support craft with the laser power-up results in three laser beams, decimating multiple waves of invaders with every press of the fire button.