Quote: "but a bit concerned 40000 polys is not so much nowdays"
That many vertices is a lot for a single entity of that type in any engine even unity and unreal, even Unity has a cap of around 25,000 polygons per individual mesh.
You can have a model with 200,000 polygons if you like, but it needs to be broken down into chunks so that it is separate meshes within one object.
For example a whole mesh with 60k polygons all connected wouldn't work, but a model made of three meshes at 20k each exported as one model would work.
It's not a cap for the whole scene, it's a cap per mesh object within each model.
It's not recommended to have objects with hundreds of thousands of polygons though because it's simply not optimal, even top end machines will have trouble with games full of objects that high in polygons, pretty much in any game engine. For example just so you can have a reference point, the Unity recommended polygon count for characters is between 300 and 1500 for mobile games, and 1500 to 4000 for desktop games, and characters are far more complex than a building.
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