gigastar said:
And in the original Potato Sack the included games had hidden bonus levels added in, completing those hidden levels earned the player a (virtual) potato. All players that had obtained all the potatos when Portal 2 released got a copy for free.
That's not quite... the whole story (yay LRR joke!). While accurate, you forgot to mention that there was a whole ARG behind it which not only lead to Portal 2 being released early for PCs (though not by much if I remember correctly) but also brought on a lot of people working together to find all the tiny clues to find the things you had to do. It wasn't just beating secret levels. The community had to find and complete these things, and do specific tasks to get 'DLC' (which wasn't actually DLC, but more of a non-achievement token to show you did it), and so on.
The reward for getting all of the things done was the golden potato, which I'm one of the holders of (had to do everything in about 1 day... it was pretty nuts). The people who completed it didn't get Portal 2 for free per say. They actually got the Valve Complete Pack, which included Portal 2 along with every other game Valve made to that point. While accurate, it's important to point out that it was much more then one game. And anyone who already owned copies of Valve games got giftable copies of those they owned.
All and all in was a surprisingly deep event that a lot of people put a lot of work into. If it's going to happen again, good. I'd like to see it, even if it does force me to work for hours straight to try getting it finished once more.