The original Maniac Mansion was good, but the sequel Day of the Tentacle is comedic science fiction gold! In the longplay embedded above, you can follow the story as Bernard, Hoagie, and Laverne fight the ubermensch Purple Tentacle. The early 1990s was the high water mark for Lucasart humor-laden adventure games. Sam and Max Hit the Road is another amazing game from that era (fuel for another post!).
Let’s Play Lucasarts’ Maniac Mansion: Day of the Tentacle