One of you must Create an "Open Mansion" map / see image below . Can be easily done using basics of 3D design inside Software or Right in Unity . But you must find some truly free 3D models of furniture and they have to be simple and each room can be some kind of room with just furniture but best to have 2 ways out of the room to avoid having locked up tight locations . And some walls can be glass . I think glass material does not work for baking light maps . But glass from Legacy - Vertex Lit works as transparent as you set in Warmerise . 
Spacetrooper said:WHY ARE THE TEXTURES SO REAL? I thought this was an actual photo for a second lol
I was about to say that it's probably something called Archviz (architectural visualisation), but then I just "reverse image searched" that photo and found this site (among others). Apparently, it's a real life model made out of a wide range of materials.
By the way, OP: Uploading and including such images here can be problematic due to them being copyright protected. You never give credit to the places where you got these images from. And quite frankly, I don't see any possibility of bringing this - or any of your other recent map ideas really - into Warmerise: They are often too complex to be considered a playable game map. Take a look at actual games that are FPS and in trend instead - be it Overwatch, Battlefield, Hunt: Showdown, or whatever you play - and get your own ideas and inspiration from them.
It does not matter where I got this image but copyright does not matter beacuse anything found on internet can be shared and it is beyond any laws to control . Copyright matters if such image used commercially such as publishing some book about making these things . Getting ideas from inspiration when looking at work of others is totally legal but cannot copy details but only general idea like in this art we see transparent walls and regular wall so it is main idea to have half of building maze walls of rooms be transparent for looks and for different gameplay .