Aperture Science adds mysterious new countdown clock

Rumours that Portal 2 will be released ahead of schedule have gained extra weight. The Aperture Science website has been updated with a mysterious countdown, ticking over the seconds until 9am Friday morning (PDT).

Australian Kotaku reader Trevor Holland has been keeping a close eye on the super-comprehensive Valve ARG wiki, and spotted the update.

The news follows a week of Portal 2-themed updates and experiments in an amazingly complex alternate reality game.

At the moment, all signs are pointing to "Probably" with regard to an early release, but some gamers are holding out hope that Friday's update will refer instead to another eagerly-awaited Valve title, Half-Life 2: Episode 3.

With less than nine hours left to go, the Aperture Science website has been updated. The countdown is still ticking over, but a note has been left underneath, written in a very familiar style.

"You have done well, humans. Very well. Acceptably well, even."

As to whether or not the clock is counting down to the early release of Portal 2, nothing more has been revealed. We're simply told:

"The time is near, humans. But it is not here yet. Tomorrow you will be given the final test. Then it will be entirely in your hands when I am freed."