This is a paid asset, but now you can download Sci-Fi Environment Free.
Detail this asset from Unity Store: Original Link
Sci-Fi Environment v1.2
modular parts for the construction of any structures or objects. All objects and models in the screenshots are built in the editor.Features:
— Low-poly.
— Completely modular design and 100% reusable.
— PBR Materials.
— Ready for level design.
— Z-fighting protection.
Inbox:
— 113 models by basic concretes, metal constructions and props. With modular design – all models easily fit together.
— 147 prefabs.
— 24 materials.
— 78 texture maps (2048*2048px).
With Stages: Industrial Sci-fi pack you can build any levels, environments, props objects and more for your game.
Texture maps created special for Standard Metallic Shader (AlbedoTransparency, MetallicSmoothness, Normal map, Emissive, Detail mask and Secondary Details texture)
World dimensions:
Recommended characters height = 1.6 meter/unit.
Wall height = 4 meter/unit.
Door height = 3 meter/unit.
Window height = 2meter/unit.
Step offset = 0.1 meter/unit.
Since all models is low-poly, you can use this package to your mobile games.
All pivots are designed in such a way that you only need to set the grid alignment and start building.
Perfect for standard unity character controllers.