Onslaught

Shoot the incoming enemies before they reach your castle and damage it in Onslaught. The game ends once your castle damage meter reaches zero.
Each shot that hits increases your super shot meter, otherwise if your shot misses your super shot meter goes down. You get an extra super shot each time you fill the super shot meter.

http://www.tutorialsto.com/flash/games-20090512/onslaught.swf