A
LucasArts point-and-click adventure game that was loosely a sequel to
Maniac Mansion (it was released after
Ron Gilbert left the company). It involved a small game
environment (like its predecessor), a
cartoony graphical style that was a departure from the previous
SCUMM titles, and some of the most
tortuous adventure game
puzzles ever written (made all the more complex by the
time-travel premise).
I think Alchemy's writeup misses the point somewhat. Maniac Mansion was an excellently designed C64 adventure game, but if Day of The Tentacle had followed its approach (instead of adopting some of the techniques from subsequent - and better - SCUMM titles) I think it would almost certainly have resulted in a poorer game.
By concentrating on a smaller core of characters and expanding the game with a (genius) time-travelling plot, LucasArts were able to make the game more focussed (and make the game more friendly to beginners, and have vastly improved production values - the animation in DOTT is fantastic throughout). I also think that the emphasis in both games in the series is oddball, unpredictable situations rather than "horror".
The moral of this story is that things weren't always better in the good old days.