Valve’s enigmatic countdown clock has ticked its last seconds, revealing the whole aim behind the game company’s crazy puzzles.

A screengrab from Valve’s final exam site

Bottom line: Portal 2 will release early, but only if players can pass a final exam.

According to a message that appeared when the clock hit zero, the game will drop early if players log enough time in the company’s Potato Sack package of Steam games.

The message redirects to a site called “GLaDOS@Home,” a reference to the main villain in the first Portal game.

The Potato Sack games provided the original clues that led players on a digital scavenger hunt. Now they have to play the living daylights out of them to move the game’s release date up from April 19.

If you’re interested in participating, you can download the 13-game pack from Valve’s Steam service for $38.65.

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