I agree with Wolf, the level design look pretty good reminds me of the city in I Am Legend, but your colours are way too vibrant, especially the skybox you have chosen, maybe try something like the cloudy overcast (i forget what it's called at the moment) one, and try adjusting the ambience and surface level colours to compliment it, as well as adjusting the brightness and contrast to give the colours a less vibrant more washed out look.
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