Think Tetris, think Columns and then mash the two together with loads of alien 'googly' eyes and you'll get the idea of YO!, in which you try and match four or more pairs of adjacent alien eyes, eliminating them from the playing field. Full of primary colours and with smooth gameplay, YO! impresses at each turn. Just don't get paranoid with all those pairs of animated eyes keeping you under observation!
Here's YO! in action:
There's a plot of sorts, something about an alien invasion, but happily the main help page is more direct:
Ah, so the aliens are called 'yos'? What sort of name is that? If they want to strike fear into the heart of earthlings, the name needs to be different. What about The Yozassians? But I digress, it's only an arcade puzzle game on Symbian, and very nicely done too...
The two left hand side slots show the 'Yos' coming up, so that you can plan ahead. Tapping left and right moves the currently falling piece one slot in either direction, while the down control accelerates the falling to the bottom of the playing field, which can save time early in the game. Finally, the bottom right control toggles the yo configuration, from 'A upon B' to 'A besides B' to 'B upon A'.
Somewhat subtly, if you opt for a 'besides' configuration, then the two halves can settle differently under gravity, meaning that you don't end up with 'holes' in the playing field. As with most similar games, when your target group of 4 adjacent matching pieces explodes, everything around falls to fill the spaces left. And if this in turn creates another 'match-4' then you start to build up score multipliers - of such happenings are high scores born....
You can buy YO! for £1.50 here in the Nokia Store. Well worth it, in my opinion.