I understand what you are going for but you should really color your blocks and use textures. Ask yourself
does this look like a building, or something out of roblox. Look at other peoples maps for an idea, nothing wrong with that, There are a lot of odd looking pieces that could really help you build a believable building.

I also have a hard time seeing how this could be balanced, you have a sniper on the most open map you could possibly have on extermination, the games will either last 10 minutes or end within seconds. Where are the trees? For extermination maps to work they have to kind of be small, this would be a solid concept if you downscaled it all together.

 

Dont be afraid to have power weapons, just try to make sure your map is good for those weapons, make sure if you have snipers you have some good cover and what not if you want it to be more fun to play on, if you want rockets keep them, it is your map dont build for other people.

 

i think the map has good concept but one criticism i have that hasn't already been covered is that looking at the features of the map most of it is made prefabs and i have no problem with using a couple of prefabs here and there but almost the entire map is made out of them and not even their colours of features have been changed again i don't have problem with using a handful prefabs but it gets to a point where instead of being an original map it's just a mess of prefabs instead.