MANIAC MANSION / LucasArts / PC
Maniac Mansion came out in 1987, just one year after LucasArts' first adventure game ever (Labyrinth). The jump in design and programming for just one year is astounding. It's also the first outing for designer Ron Gilbert, adventure game legend who would go on to create the first two Monkey Island games.
Aside from the impressive jump in overall level of polish, what's really amazing about the game is that it dives straight in to some technically complex territory for 1980s adventure games. You pick 3 characters from a roster of 6, each of whom have unique abilities that allow for multiple solutions to puzzles. That's complex enough by itself, but Maniac Mansion also adds the twist of NPCs who can roam the game world! Many gamers undoubtedly got a shock when they first entered the house and ran face-first into Nurse Edna in the kitchen; but it was even more of a shock when leaving a kid waiting in the foyer led to them getting ganked in a cutscene when she came back from her munchie run! Granted, they don't do roaming NPCs *much* (and granted the pathing is simple and they just kind of give up and go back about their business if they're chasing you and you duck into another room), but for 1987 and only a second adventure game outing it's impressively complex.
While the game is really good on all counts and still quite playable, some aspects of it have aged poorly and there's some questionable (inexperienced) design on display. It's one of the few LucasArts adventure games where you can both die and stick yourself in an unwinnable position without realizing it. There's only a handful of ways to die and most involve doing something screamingly stupid, so those aren't really an issue; the hang-ups are much more of a problem, exacerbated by the game's free-form style and total lack of a narrative. There's a number of ways to screw yourself over permanently and not realize it. Usable items on each screen also aren't revealed when you "mouse over" like they are with later SCUMM engine games; there's a What Is command you have to select to get an overview of everything on the screen you can potentially interact with. Menu commands also could have been condensed a bit better; is it really necessary to have a separate "turn on" and "turn off" command?
It should also be noted that the screenshots here are from an enhanced graphics version released a couple of years later; the original release from 1987 looks much more blocky. Aside from all that this game is deservedly an adventure game classic and a must-play. The PC re-release is your best bet due to the enhanced graphics and lack of censorship.