Rubble? As in, the remains of long-destroyed or eroded away structures?
Right now, all those light beige dots/rocks just looks like a different type of natural earth/ground, to me.
Why that prominent vignette? Makes me feel like I'm viewing the world through a telescope or something.
I assume you're just trying to make the world look less spot-colored and want to introduce some gradation for enhanced impact/depth. Which I agree with, but I think your execution is lacking.
See a
Hyper Light Drifter example of gradiently shaded low-res pixels.