I can help you with the map setting ideas, becouse you might consider that the city of boxes isn't the best place for a gun fight, right? :) Just leave a quick note if you are interested.

I'm currently working on a large update to this map. The update will contain a better skybox, as suggested by "Bad Luck Panda" aswell as some improvements to the 64unit boxes (tetris).

http://www.tophattwaffle.com/tutorials/
Especially turorial 15 should be for you.

@bad luck panda, do you perhaps know a good tutorial for this matter?

Improve your 3D-Skybox. It will benefit the overall look of the map quiet heavily if you do it right. Add Details around the non playable area of your map, because as it is now, it just looks boring.

As writen in trhe description: I am gladly taking some critisism about my mapmaking so that I can improve! Thanks for trying it out!