I also duplicated and recolored this tileset to make some background tiles.
That may give you interesting effects, but my impression is that it isn't that sexy for a background.
I mean, that'd be great for having small places that are open space but that should remain somehow "hidden", like sub-caves to explore, but for the general, open-play area, i'd discourage this
- because it makes reading of what's open and what's closed space harder (little contrast between both, no hue difference)
- because whatever is further is also less detailed to our eyes.
- because background is a unique opportunity to bring something that is absolutely not squary and tiled.
How about huge rocks instead ? or even some kind of oversized glowing mushrooms or whatever would fit your game's mood. My impression from those tiles you've done is that they are a stunning base for those kind of "exploring an hostile alien planet" game we used to have in the 8-bit era.
(
http://www.itchstudios.com/psg/exile/exile-ish.htm could show you what i've in mind)
Now it's up to you. Do *you* think those darker tiles make a good job ? what kind of environment did *you* intend to have ?