Want to unlock Portal 2 on Steam ahead of its published 22nd April launch date? Then you'd better get stuck into the Potato Sack indie bundle.
To force an early release it seems you'll have to go and play the various Potato Sack titles until a "computation" bar has filled up.
At the time of writing, another countdown clock projects the game will unlock on Steam in 93 hours and 30 minutes. If you want to speed things up, you'd better check out those indie games.
For the uninitiated, the Potato Sack includes 13 indie titles: 1... 2... 3... KICK IT!; AaAaAA!!! – A Reckless Disregard for Gravity; Amnesia: The Dark Descent; AudioSurf; BIT.TRIP BEAT; Cogs; Defense Grid: The Awakening; Killing Floor; RUSH; Super Meat Boy; The Ball; The Wonderful End of the World and Toki Tori.
It's available now for Ł27.22 via Steam.