The player controls Casper, followed by Kat Harvey whom he has to protect from any danger. Being a ghost, Casper can pass through walls and other obstacles, but he can't go away from Kat too much, or else Carrigan's ghost will abduct her. The game follows loosely the plot of the movie. This game uses a revised Absolute A Boy and His Blob engine. Picking up special objects allows Casper to morph into these objects to clear rooms of enemies, and to protect Kat from certain hazards. Mirrors placed throughout the game allows Casper and Kat travel to other parts of mansion, and outside electrical lines allow Casper to pick up the last of the toys, when he picks up the electric bolt morph.

Casper is a 2D Platformer game, developed by Planet Interactive and published by Microids, which was released in 2002.

Casper plays as a top-view action-adventure game with pre-rendered graphics. The game consists in first finding tokens of friendship for Kat and Dr. Harvey, then finding the pieces for the Lazarus machine, and finally finding the Cellular Integrator (which Carrigan's ghost, who serves as this version's final boss, steals, leading Casper to her lair) while exploring the mansion and dealing with Casper's uncles (especially in the second act, as his uncles as well as different variants thereof [like Gravedigger Stretch, General Fatso and Hedgecutter Stinky] guard the pieces of the Lazarus). Unlike other versions, other than the Ghostly Trio and Carrigan, there are no enemies. The game instead focuses on solving puzzles.

Based on the hit movie, CASPER for the Game Boy follows the adventures of everyone?s favorite friendly ghost, as he explores Whipstaff Manor in this adventure or puzzle game. As Casper, you must use all of your wits to solve the riddles and mysteries that surround the mansion. Collect items and use them carefully to open up new rooms and puzzles, and see if you can uncover the secrets of the estate.