"The gameplay of Luigi's Mansion 2 is similar to its predecessor. The game focuses on the adventures of Luigi, who is sent by Professor E. Gadd, through teleportation, to explore various haunted mansions (at least three), and capture ghosts using the Poltergust 5000, a specialized vacuum cleaner, which can also be used to gather treasure hidden in various rooms. Clearing the rooms of ghosts award the player keys, which open access into deeper areas of the mansion." Source: Wikipedia, "Luigi's Mansion 2", available under the CC-BY-SA License.