I started this level with a BSP block-out in UE4 to get a good gameplay first.
I then created a master material for the floor and created some basic meshes in 3ds Max to get a basic feel for how I wanted it to look. The next step I took was to create a trim texture that can be used with the master material with the use of a few grey-packed textures that act as a mask for the dirt, stains, scratches, and those multiplied with a mask for the edges to get more localization there. I then started with making more detailed meshes and applying the trim texture to them, which I then placed all around my level.
The last thing I did to make it a bit more appealing was to create some water around it all so I began creating a shader for the water: eventually I ended up with 2 material functions for the overlapping and deformation of the water and in the water master material generated the foam by using mesh distance fields.
The guns & health packs were made by Epic Games.