It's not necessary to have played Maniac Mansion beforehand? I'll admit this has been my main hesitation. I remember when Monkey Island III was big in the late 90s, I was hesitant because I hadn't played the two games that came before it.

I ended up doing it anyway at the time, but later I would play all three, and the third one really benefits - in my view anyway - from having played the first two ones, even though they can all stand on their own. So I wonder whether Day of the Tentacle is similar?