From the Super Mario Wiki
There are robot's legs at the bottom of the screen, which the player controls with the /. The other two sections of the robot (torso and head) are falling from the top of the screen. The player must move the legs to catch the other two parts. They do not need to be aligned; the bottom of one part just has to touch the top of another.
In WarioWare Gold, the robots are thicker, making them easier to drop down. The 2nd and 3rd levels have also been changed to different robots.
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