Steam’s mega holiday sale gets interactive

It’s not at all unusual for Steam to launch a gigantic holiday sale encompassing Christmas and New Year, but this year Valve has added a twist by encouraging buyer participation. Alongside the usual collection of daily deals, publisher deals and deals on top of other deals, Steam users are being enticed by ‘The Great Gift Pile’; a chance to get yourself even more games.
How, exactly, does this work then? Well, it’s helpfully explained with a flow chart, but I’ll have a go at detailing it too.
Every day (until the sale ends on 2 January), six ‘objectives’ will be set. These will be things to do in games that may or may not be in your Steam collection (for example, today there’s one for Cargo!, which I own, and Orcs Must Die!, which I don’t). Complete the challenge in the game to win either a free gift (which could be a game or a money off coupon to spend), or a lump of coal.
Those lumps of coal aren’t useless though, because if you get seven of them you can craft them together to form a guarenteed (albeit still random) gift from the Gift Pile. If you’d prefer to hoard them, each remaining lump of coal on 2 January will also count as an entry into the ‘Great Holiday Giveaway’ with a grand prize of every single game on Steam. Yowser.
Both gifts and lumps of coal are tradeable with your friends (or indeed strangers), too. 
Be aware that Steam’s servers are taking a bit of a beating at the time of writing, so your disposable income may be safe for a little bit longer.
Source: store.steampowered.com