I can elaborate on the graphics. It's all too bright and has too much sharp edges. To improve it you could darken the floor, apply a texture of some sort (carpet, wood planks, anything to break up the repetition). Make the floor tiles checkerboard less prominent.

If you wanted to add some volumes to the walls, you could have made them drawn at an angle (like old rpg walls) so you could see the front face of the wall and a little bit of the top face of the wall. Or you could have used a frustum pyramid instead of the whole pyramid, that would have too reduced the amount of sharp angles.