Myst
Monkey Island
The Walking Dead
Riven
I think I give the nod to Myst over Riven due to its impact, even though I think you'd be hard-pressed to argue Myst is the better game. Though at the same time, Riven is so much better it's ridiculous. Monkey Island over Maniac Mansion feels wrong somehow, but eh. Something from the Telltale renaissance has to make it in, and then I'll give the fourth slot to Riven out of blatant favoritism. It should probably be Zork though.
Nonsense. "Testing" is for when you're still guessing--and now, I have no need to guess. -- Agatha, Girl Genius