I had a few goes with Light & Shadow and I was quite set to give it a sound verbal thrashing and to send it on its way. Luckily I caught on in time and am now quite happy to sing Light & Shadow's praises.

Explaining the trick to the game is rather on the difficult side, and I wouldn't want to ruin the surprise anyway, so I'll just provide a basic rundown of the game mechanics. Your playing area is an 8-by-8 grid, filled mainly with "light" or "shadowed" pieces. They look blue and brown to me but, hey, it's their game. At least one of the grid spaces is empty, and it is here that you make your moves in the game. Clicking on a piece on any of the four sides of the empty square will flip that piece over into the empty space, flipping a light piece to a shadow piece and vice versa. By flipping over the block so as to form a line of four (or more) of the light pieces, you will gain "white energy", which will fill up a bar at the bottom of the screen. Fill the bar and you can progress to the next level.

Preventing you from doing this are the shadow pieces, create a line of four shadows and you will score dark energy, not only does this negate your white energy but it is also worth twice as much as the white energy making failure by "turning to the dark side" a distinctly easy trap to set yourself up for. Filling up your dark energy bar will end your game.

Creating lines will turn every second piece in the line over, starting from the last piece you placed. Basically, the piece you moved doesn't turn over, but the two next to it do (and the two next to them don't and the two next to them...). Long chain-reactions of lines are possible, with pieces in light lines flipping over to complete shadow lines, which flip over in turn to give more light lines and so on. This can in cases either make or break your level, depending on how things are arranged at the time. Due to an odd quirk of mathematics, the pieces-in-lines-flipping-over system seems to force each level to end up as a grid of alternating light and shadowed pieces if you play for long enough without completing a level. While this definitely adds in a certain possibility of getting stuck completely without being able to ever finish the level, it's actually pretty near impossible to do so due to the good level design.

As well as these basic mechanics of the game, Light & Shadow features quite a few other types of playing piece. Some of these are just higher-scoring versions of the vanilla light and shadow pieces that fill up your bar more if you form a line containing one of them, but a lot of them are quite interesting, such as neutral pieces which can prevent you from making lines and their opposite, pieces which can form either light or shadow lines.

Overall, Light & Shadow is an extremely competent puzzle game and is well worth a look if that is at all your are of interest.