The game you have going looks solid, but you should really look into ways of improving your art assets. Even putting quality aside, it's really inconsistent how much certain objects stand out. The trees and tanks are really bold and look like they should be solid foreground objects, but they're part of the background. Inversely, the crates are really soft-looking, like they shouldn't be solid even though they are.
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your colors aren't the best combination and some stuff needs to stand out more (like the gems) and some a little less (like the windows)
maybe i could help u with colors??? i have a couple examples i can pm
