Find out where you can play the classic MS-DOS version of Maniac Mansion online for free.
Where to Play
You can play the MS-DOS version at Archive.org for free. Click the game screen, then if your browser pops up a message asking you to disable the mouse (or something similar), allow it. You can right-click to cancel cutscenes and messages. There is no way to save the game in the Archive.org player. Read the MS-DOS Emulation FAQs at Archive.org for more information.