This game can be played either with the keyboard or the mouse. The goal is to get the green blocks to the finish. Use the arrow keys or click inside the level to make the blocks fall left, right, up, or down. All blocks must fall until their path is blocked. Darkened blocks are stationary. The types of blocks are listed below, but you'll learn them as you go if you play the game.

Green Blocks: When all green blocks have reached the goal, the level is completed.
Wooden Crates: A basic block.
Steel Crates: These crush any wooden crates they happen to land on.
Reinforced Crates: These are like wooden crates, but can't be crushed.
Spikes: These can crush wooden crates like steel crates do, but they can also destroy the green blocks. They also destroy blocks that land on them rather than just by landing on other blocks.
Polar Blocks: A red and a blue annihilate each other on contact. Two grey blocks also annihilate each other and do not interact with red or blue blocks.

In some levels, it is necessary to destroy certain blocks and in others the blocks need to be preserved in order to reach the goal.