The version published by Interplay plays as a top-view action-adventure game with pre-rendered graphics. The game consists of three acts, first finding tokens of friendship for Kat and Dr. Harvey, then finding the pieces for the Lazarus machine (which Casper's uncles had disassembled under the impression he would use it on himself), and finally finding the Cellular Integrator (which Carrigan's ghost steals, leading Casper to her lair) while exploring the mansion and dealing with the Ghostly Trio (especially in the second act, as Casper's 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 (who serves as this version's final boss), there are no enemies. The game instead focuses on solving puzzles.
Source: Wikipedia, "Casper (video game)", available under the CC-BY-SA License.