[Uatu]

It would definitely look better than just boring ol' black, but one thing I am not sure about is what to do with those creatures that can be encountered in several places. For example, sprites would be fine with a green background (or I could just paste the small pic onto my forest picture); but a giant rat could be encountered in both the forest or in a dungeon... Two versions of this small picture, then?

But a simple colored background would be a simple way of adding some kind of background, I guess...