In a very surprising move, Amazon have released their own gaming engine for all to have a go with. And giving this even more of a twist is that it will be completely free, no download cost or royalties to pay.
 It's a very nice, and one that might make Unity and Unreal 4 have to have a long think about where they stand, because if Lumberyard gets the support from the gaming public and enthusiasts, it will become the go to engine.

Link to the download here.