What level of colorblindness? Hard to see the difference between certain colors or completely black&white?
This is probably a bit too dark already, but it might give some ideas
Like wakka said, you could make the walls have big areas of flat color without detail and then show some battledamage and details here and there that show the material of the wall. Like a big block of grey can become a wall if you add just a few cracks in the corner that reveal some of the things under the surface.
Post the player character on the picture as well to better show what kind of direction would be best for the backround.
!Off topic!: I tried the intercept game last night, it's really good.
I got a highscore of a bit over 2million.