I will cut myself!
Whohoho, this is so bad!
-Textures
-Relfections
-Materials, basicly
-The art in the scene
-Background...
It's not worth even reviewing! Please, it's torture for my eyes!
Try fixing:
-Shadows
-Reflections (Shells look transparent as GetAwkward said)
-Materials (Bullets look like they have no material, try increasing reflection amount a bit)
-Textures UNREALISTIC!
-Background, do you see it? Neither do I.