According to the blurb, the world that you been have uttered from is under attack, so you naturally 'fight back'. All to do is fly your ship over a series of seven grids, each harder than the previous one, shooting nasties and some funny dome-shaped things. And when you have shot the requisite amount of FDST (Funny Domed Shaped Things), you get transported to the next grid.
Occasionally, an item appears under the grid, so you must use the Dive button to go under the grid, collect the thingumibob and climb back up.
When you've destroyed all seven grids, then it's off to the city again to cause a lot more mass destruction.
Graphically, it's dull. Aurally it's dull. Even the playability isn't up to much. So I can't understand why I quite like it. Maybe because it can be fun. Approach it with the right attitude and it is FUN.
Just one more thing. It claims to be 360' scrolling. I'm sure it only scrolls in eight direction.