What language did they write in? What kind of features does the language have? I'm curious how you would design such a language.
Here's the official manual for SCUMM: http://wilmunder.com/Arics_World/Games_files/SCUMM%20Tutoria...
And the official tutorial: http://wilmunder.com/Arics_World/Games_files/SCUMM%20Tutoria...
There are several post-mortems about Maniac Mansion that go a bit into the creation of SCUMM: * https://www.youtube.com/watch?v=wNpjGvJwyL8 * http://www.gdcvault.com/play/1014732/Classic-Game-Postmortem...