Scrap the hazard line for the bars in the HUD. Hazard lines are ULTRA CONTRAST because they are designed to catch people's attention and they are absolutely dominating the priority hierarchy of the piece at the moment. Not something you really want for a HUD; if the player wants to check something there, they'll deliberately glance at it.
I agree about losing the white outlines, as well, for similar reasons.
The background is very patchy/blotchy, which kind of gives it the effect of noise. Perhaps try a more composed arrangement for the clouds.
The mix of cool and warm speculars on the sprites and tiles is disharmonious. I do like the priority gained on the sprites by the temperature contrast, though. One thing that could work is to not make the ground tiles so... specular-y. Shade them more according to planes, rather than edges and corners. This will make the warm light appear to be ambient, rather than direct, "sort of" explaining the temperature difference. Or you could match temperatures on the sprites and tiles, but hue shift them in opposite directions.
The floating stone blocks don't really fit at all, imo. The fact they differ so drastically in both theme and shading approach to the ground tiles is a prime reason for this. Also the fact that everything else in the scene has some physical explanation for its state (jets on the mines, junk in realistic piles) whereas the stone blocks are inexplicably floating. Oh I guess the missile pack pickup is floating too... I actually didn't even notice that was there until just then. Might want to increase it's priority a little by differentiating it's palette from the other elements (similar to Batlorder's suggestion on the player's ship).
Keep it up!
