Me personally, I would add a skybox to the map. Skyboxes can make a world of difference. They look infinitely better than just the default settings. You should also mess with the lighting, as the lighting currently looks a bit dull. I would assume for a UGC game, you would have much brighter lights and a more lively ambience. As your game grows, work on making the map a lot more interesting as well. Right now, it is a bit too simplistic.
Some things that I liked, were your UI and the textures you used for the build. I think your game has great potential, as your UGC is pretty good, and much better than a lot of generic UGC games I see on the platform.