update
added ribs on the dome, added four more characters, 2 of them are still just volumes, and the rat is still ugly,
do you have any suggestion on how to render the wet fur of a rat?
Thanks for your comments,
@TrevoriuS: with ribs the dome is really better, thanks for your advice
@Jim16: it's true that light is not so consistent, being material for a platforrmer game, I think i will leave light on characters like it is now (from above) so that i do not need to draw them twice (facing right and facing left), maybe i will try to change lighting on the walls to comply, and see what happens.
About the usage of black for platforms your suggestion is interesting, but i would like to keep dark platforms, maybe I will try to use more light colors for the top of them, so it gets clear it is a section view.