The difference between SCUMM and something like "Celeste Engine" is that Gilbert and the rest of Lucasfilm Games decided to reuse Maniac Mansion's code for thei

The difference between SCUMM and something like "Celeste Engine" is that Gilbert and the rest of Lucasfilm Games decided to reuse Maniac Mansion's code for their next titles, while nothing reused Celeste's code (yet). SCUMM even has it in its name ;)