Hide and Boo Seek

From the Super Mario Wiki

Hide and Boo Seek.

Hide and Boo Seek (also known as Boo Wipe) is a mini-game in Super Mario 64 DS, where Luigi must use his Flashlight to find the Boos in the mansion. The player must use their Stylus as a flashlight. In the intro, the player would see the Boos. The lights would then turn off. The player would then have to find the Boo(s) in the dark in three seconds. If the player found the Boo(s), they would move on to the next level where there were more Boo(s). After level fifteen, the amount of time was reduced to two seconds. If the player couldn't find all the Boo(s) they would get a "game over".

The Boo(s) in the game follow basic physics, bouncing off walls and each other at angles relevant to the angle they hit them at. By observing the Boo(s) at the beginning, the player can predict where they will end up.