From the Super Mario Wiki
Mouse Trap is a microgame found in the Nature folder in WarioWare, Inc.: Mega Microgame$!.
There's a mouse that runs side to side. The objective of the game is to drop the trap dome when the mouse is directly under it.
- 1st level difficulty: The dome is 1.6cm in diameter.
- 2nd level difficulty: The dome is 1.2cm in diameter.
- 3rd level difficulty: The dome is 0.8cm in diameter.