I like the color palette you're working with here. I do think the scene could benefit from some atmospheric haze however. To me it seems as though the saturation of the largest mushroom and the blocks of the darkest value are competing for my attention and the tangent between the two flattens your world. I think a little atmosphere would be a quick way to give the illusion of depth.
This is a great composition, love the sense of scale. I agree with Briton in the idea of more atmosphere, just a blue wash layer overtop. Perhaps have it a bit more extreme on the moons and gas giant as well, even to the point that its nearly difficult to spot from the sky, like the deathstar shots from Rouge 1, and maybe get some volume shadows on there as well. https://www.wired.com/wp-content/uploads/2016/07/Rogue-One-Poster-692x1024.jpg
That Star Wars reference was the best critique inspiration I've ever received! ,_~"""~-, .'(_)------`, |========| `,---------,' ~-.___.-~
Good value structure & clarity. I would second the comments above. Overall, I would say this piece could use a few more grays and neutral colors to help offset and feature the saturated colors. It can be tricky to figure out how to indicate a very warm local color on an object (like the giant mushrooms) at a distance through a blue atmosphere. Study the work of the French Impressionists, Hudson River school landscape painters, California Impressionists, and contemporary artists. Also remember some subtle complementary colors can help create an unexpected richness. Also remember anything seen in the sky, like the large planets, needs to have much more subtle color in order to really feel as far away as you want it to. With such a blue sky, it really only takes a little bit of pink (or gray, in fact) to indicate the warm local color of the planet. Give it a try and you might be surprised!
I think this is great! I love the composition and the giant mushrooms. Scale is working well and I really get a sense of how big things are compared to your characters. I think the things I would suggest are you add some more atmosphere for more dimension and toning the color saturation down and add more neutrals. Another thing to think about is the context of the rectangular building/stone structure. I'm just curious what it is exactly. If it is just a stone structure then adding some similar like it in the distance might be good.
Well I wrote out a long reply but then Blogspot didn't publish it...so here it is again:I like the concept and the multiple planet moons.I like the rock structure on the left and I wish the structure on the right matched it. Right now the round shapes compete with the roundness of the mushroom and the moons, but if they were both those sharp shapes they would lead the eye to the giant mushroom.