You are doing your basic training to become a full-fledged Ghostbuster. As part of your training, you are required to spend the night in a haunted house and get rid of the ghosts inside.
Notes
The game is called 'Gh0stbusters: Basic Training' (with a zero) in all the game files, including the readme file and the game itself. However, some online sources have wrongly called it 'Ghostbusters: Basic Training' (with the letter 'O').
This is no doubt inspired by the 1984 movie 'Ghostbusters' directed and produced by Ivan Reitman.