Ghost Master
Ghost Master is a 2003 game developed by Sick Puppies Studio and published by Empire Interactive. The game is a single player Strategy/Puzzle game in which the player assumes the role of a titular Ghost Master who commands an army of ghosts to do their bidding in order to cause as much terror as possible in a fictional town of Gravenville.
The game has fifteen levels split among three Acts and an Epilogue. Each level (Besides the bonus level) has at least one restless spirit which has an unique puzzle requirements in order to free them and add them to your team.
Story
The game starts with a group of mortals gathered in the Ghoul Room in order to commune with the dead using a Ouija Board. They accidently open the gate between the mortal world and Ethereal realm, allowing ghosts to cross over and begin the haunting campaign.
The overall plot of the game revolves around freeing an ancient spirit known as the Darkling which is later captured by a mad professor, Dr. Krauss as well as a mysterious mortal known as Dr. Brunner. Most other levels have a self contained story (with few exceptions like The Calmityville Horror and Poultrygeist) which don't feed into the story at large. During What Lies Over the Cuckoo's Nest?, the Darkling is freed and Dr. Krauss has his soul devoured. The game initially ended on a cliffhanger in which the Ghostbreakers create the Ether Bomb in order to destroy all ghost matter in the city. They place it on a train headed to the outskirts of the Gravenville in order to detonate it.
Few months after the release of the game, an additional scenario named Class of Spook 'em High was released which added a new ending in which the Ghostbreakers take over the Ghoul Room and place the bomb in the same room the initial summoning took place. The Ghost Master storms their base in order to disarm the bomb and scare all the present mortals away. After the mission, a portal to the Ethereal world opens and each haunter you freed goes into the light, ending the haunting campaign, with each ghost finding peace in the afterlife.