Extile layered materials were used for the environment material texturing. Extile layered materials can be found in Extile Plus and represents the most versatile way to layer materials in a non destructive and easy way coupled with some of the most powerful non-repetitive functions giving you the power to texture any type of environment with absolute control and with great speed.
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Example I: For the prison floor I used 3 layers. I used a RandGeo layer to create a non repetitive tiling floor this way no matter what I didn't have to worry about tiling issues. It also comes with world aligned settings if you want to have the texture in world space orientation. On top of that I added a tiling cement texture but used the non-repetitive random blend to give the feeling of certain tiles removed and replaced with cement. (In the actual game I used this technique via a decal setup to give me some more control on placement as these patches appeared in certain specific areas.) Extile comes with a variety of blends but one of my personal favorite is the vertex mask which I have used to blend in some dirt in a third layer. You can adjust the display blend amount to get some nice blending. In addition you can use in conjunction with vertex painting if needed for more control.
In the last image you can see a more layered blend to create the floor on the tiled ground that covers a large area and can be adjusted to other parts of the game by switching off any layers that don't fit the narrative.
In both cases the floors are simple 4 vert planes as Extile's non-repetitive functions and layers eliminate any repetition without the need for more complex meshes. In addition using them in world aligned space can ensure that all the flooring parts have seamless joints.