It's most definitely a price error, given this game only just came out this year. Get it while you can :)
GamersGate account required (registration can be from any country, although the freebie link is only available on the UK site). Redeemable on Steam, available for Windows/Mac/Linux.
Edit: Deal marked as expired - however you can still attain the game but there are no keys left (Gamersgate does state they will supply the key eventually but due to the nature of this post nothing is promised).
@Elijha:
Same here. A week later since my last message and the game is still on my account. I did also install and run the game for about 10 minutes. I was also an existing Gamersgate customer having previous purchases.