Portal

Portal was an ambitious attempt to tell a story with the depth of a novel and the interactivity of a game, sitting somewhere between interactive fiction and simulation of a computer system.

Where are all the humans? Upon returning from your 100 year voyage in the milky way, you find earth empty and abandoned. Between the decaying remnants of civilization, you discover a terminal for Worldnet, the global network that recorded all human activities. The answer must lie deep in its database. Anxious, you log on.