Use WASD or the Arrow Keys to move. Use the mouse to hover over a pair of blocks and click on one of them to swap their positions. When there are three blocks of the same color in a row, they'll break apart.

You can hop on black flashing boxes to make them explode. If you see a white spark fall from the sky, run into it to slow down the rising blocks.

Don't touch the sensor at the top of the tower, and make sure a block doesn't fall on your head!