How do i make this look better

[Claustr0]

I made this whole map in a single day, i really tried my best today since its my first time ever decorating a map. It still feels extremely off though, the theme of the map is that australium has been found underwater so red and blue are fighting over it in this small platform. Im really having trouble filling up spaces and making the map feel more "alive". Any feedback is helpful

 

[Cyberen]

Make sure the map flows well. Then add props to limit sightlines and provide pathways to jump up on. Maybe some tire track overlays on the floor and trucks out-of-bounds to show the place has been used as an industrial site.
An offshore oil rig idea sounds good, look at pictures of real rigs and see how you can change the architecture and texturing to more closely resemble one.