oh nice and moody. i'd suggest though, that now that you have the basic tiles for those sets add something theme-specific. you know, like icy slides for the snow one and maybe even geysers, or liane-swinging action and coconut throwing monkeys for the first, crumbly platforms and obstacle-thornbushes for the last.
as for the bg, how about a simple sandy desert, yellowish not red, to avoid monotony, with a light blue sky and if the engine is capable of this some sort of heat haze