Nice

This one here is okay, It does need a bit of textures and overall shading. You have the ability to make something 3D, but now you need to add your elements of textures, shading, and even some light. You have gradiants going on here, and that can work for shading, but you do need a lot more. Mostly you need more details and textures will help you with that the most. I do find this to be good work tho. I know most 3D images don't render backgrounds, but if you do use this for a game, do not forget your background, or it will feel incomplete. As far as shaping for the structures goes, you did excellent, nice symmetrical shapes and frames.

~~THINGS TO IMPROVE ON~~
Needs some details and do not forget to add a background for your game.

~X~