The concept's not exactly new, but developer Quanma has done a good job with the implementation here on Symbian - the idea is to gradually segment off parts of an alien-filled playing field without getting killed (run over) in the process. With atmospheric graphics, free and commercial versions, there's little to complain about here.
Here's The Filling in action:
Dont switch off because this looks a bit drab - the circular aliens drift by, Asteroids-style, underneath this simplistic main menu - though I do think the developer could have put in a little more effort in terms of a splash screen? There's the option to turn off sounds, though you only really get a chime as each level starts, occasional pops as you clear an area, and a horrible scream when you die - there's no pretense at a full digital music soundtrack.
You get 8 of 48 levels in the free version, with a gradual increase in difficulty and variety of aliens; note though that you do get the full 'play til you've lost all your lives' arcade version included for free.
As the aliens bounce around (and off each other), your character has to make dashes across the playing field, either in a straight line (above) or...
...nibbling out rectangles. You only 'get' each area cleared if you make it back to the perimeter with no aliens crossing your just-drawn line though - any incursion by an alien and you die - horribly....(!) In the episodes mode, you get to try the level again, of course.
As you clear space, the background image is gradually revealed, which is a nice touch, and there are a wide variety of backgrounds included here. At a certain percentage cleared (shown graphically by the blue 'fill' bar's marker), you're awarded the level.
There's great playability here and great longevity too, with an inherent randomness in the alien movements and interactions.
Very nice indeed, despite the 'verison 1' implementation here. My only playability complaint would be, somewhat unavoidably, your fingertip that traces out the character also rather obscures your view of the centre of the action for a split second.