Good use of few colors. Though I do think the ramps themselves could be a bit better.
The use of black reminds me of old Sunsoft NES games... Love it!
This piece relies a lot on the balance between black and darkest-blue, it's tricky because the contrast between those two colors can be very different from one computer screen to the other. Also, because of the gamma effect, the apparent contrast becomes stronger when you zoom in. So if the game is designed to be viewed in 200% or something, you may want to fine-tune the palette while looking at the image at this size.
Thank you all!
Ottbot. It has a lot of influence by Sunsoft, specially Batman and Journey to Silius :)
Yrizoud. The palette cannot be tuned since it's the NES palette hehe..
PixelSnader. Thanks, I might have to work on the dithering more :)