I really like the direction this is heading! The dark ground works very well in conjunction with the faded background to establish a clear foreground.
as far as the rays of light go, I don't know why it's even an issue. As st0ven said, this is a game mockup. Besides, a hard edged light would clash with what I assume to be the target rendering quality. If anyone is really concerned about "purity" in the end product, think of it this way... The tiles and characters will be put through pixel refinement, which means AA. The light, therefore, should also go through AA, and because of it is not a static element drawn directly in the characters or tiles, the AA is attained through its transparency. It is, in a way, AA'd against the background colors via varying levels of opacity.