The first PC game based on the film was the Casper Brainy Book which was developed by Knowledge Adventure and was released in May 1996.

It was aimed at children aged 4–8 and is an interactive storybook, similar in style to Disney's Animated Storybooks, in which players read and play in the story and there are three mini-games, Fatso's Creature Feature, Stretch's Shake Rattle and Roll and Stinkie's Peek-a-boo, designed to teach vocabulary, spelling and shape recognition.

Although Carrigan and Dibs are cut from the story they appear in the hard jigsaw puzzles, among stills from the film, in Fatso's Creature Feature.

Narration was provided either by Joe Nipote or Hettie Lynn Hurtes, depending on if the player clicked on Dr. Harvey or Kat on the front page.

The version published by Interplay and developed by Funcom plays as a top-view action-adventure game with pre-rendered graphics.

The game features an alternate rendition of the film's plot (with some of its dark elements retained) spread across three acts, consisting of Casper finding tokens of friendship for Kat and Dr. Harvey, then finding the pieces for the Lazarus machine (which the Ghostly Trio had disassembled to prevent Casper from using it) and assembling it, and finally finding the Cellular Integrator with which to restore Harvey (which is stolen by Carrigan, leading to the final challenge), while exploring the mansion, collecting jigsaw pieces to solve puzzles for morph icons, eating food for morph points and dealing with the Ghostly Trio.

Like in the Brainy Book, Casper and his uncles were reprised by their respective voice actors, whilst Kat and Dr. Harvey were voiced by Tanya Krievins and Blair Bess (again replacing Ricci and Pullman), with Bess providing narration for each act's introduction as well as reading out several hint parchments found throughout the game.

After the Harvey's go on vacation, Casper's human friends throw him a party to cheer him up but a revived Carrigan turns them into ghosts, using a magic spell from an old book in the library, and hides them somewhere in the manor as revenge for being tricked out of the ultimate treasure.

There was supposed to be a sequel as stated in the ending and the manual where the player would help Casper turn his friends back into "fleshies" but Morning Star went bankrupt before it was made.

It's up to Casper to help safely guide him through each of five levels using various transformations and objects to help the zombie Doctor collect flasks with the formula to cure him.

The Ghostly Trio show up in each level occasionally to scare Dr. Harvey and throw him off course and Casper must deflect their attacks.

[5] A critic for Next Generation agreed that the graphics are exceptional, noting in particular the ghosts which have true transparency (an effect generally thought to be impossible for the 3DO).