Harrison Krix's replica Half-Life 2 gravity gun looked incredible, but it was never destined for his shelf, or that of an international adult collectible retailer. It was built for charity, and it's for charity it was auctioned.

Awesomely, the gun went as part of a Child's Play auction for a whopping $21,000. That'd be a bargain if the thing actually worked.

To celebrate, he's posted a lengthy explanation on how it was built over on his website, along with the above snappy video showing it in action.

Half Life 2: Gravity Gun [Volpin Props]