How to see geometry

So. 108758-anyway.png

I am making a game with no textures (I just make and paint objects with basic colors in Sketchup then export them straight into Unity), but I am facing this one problem, that is, geometry cant be seen in dark, is there any way to deal with it other than use textures?

Adding Secondary Light with low intensity Worked really well Geometry can be seen in dark, with no problem, thank you!