Klax is a block-stacking game that could be considered in the same class as the classic Tetris. As the blocks fall down the ramp, catch them with your paddle and drop them into the bins below. If you end up with 3 or more blocks of the same color in a row (vertical, horizontal, or diagonal), they will disappear, you'll earn points, and you can continue. Only five rows of blocks can fit in the bins. If the bins are full or you miss a block with your paddle, it will fall into the "deadly drop zone". If too many take this path, the game ends. If you catch a block, but you don't want that color, you can send it back up the ramp, but remember, it'll come back. Each wave has an objective that you must meet, whether it's making a number of horizontal or vertical rows, catching a certain number of tiles, or scoring the required number of points.
Images from www.atariage.com (used by permission)
Descriptions from www.atariage.com (used by permission)