Tetris Online. Free The Key. Entertaining logic game in which you must move each stone block in order to extract the key. Each horizontal block can only move horizontally and on the line itself where it is placed. The same happens with each vertical block that can only move in the same vertical. The key will only move if the path to the exit is completely clear. Each level you manage to complete will give you access to a higher level of difficulty. The game has 40 levels, 40 different ways to release the key.