To tell the truth, this game is scumm... no, really! Scumm (Script Creation Utility for Maniac Mansion) was a special game engine created by LucasArts, for the purpose of creating a good story/adventure game without requiring the player to type in all the commands one by one. Maniac Mansion, originally programmed for the PC, was later converted to the NES as the first NES game that LucasArts ever developed.
Of course, every great game needs a special something to create a wide appeal, and this one is no exception. Maniac Mansion is so chock full of different things you can do, many being very silly and many having nothing to do with the plot, but are good for the amusement. Many classic gamers who have played this game would agree that is one of the best NES games you can find... and the wackiest!