3d assets and environment:

1)

https://www.unrealengine.com/marketplace/en-US/product/storage-pack

2)

https://www.unrealengine.com/marketplace/en-US/product/sci-fi-interior-04

3)

https://www.unrealengine.com/marketplace/en-US/product/zombie-police

4)

https://www.unrealengine.com/marketplace/en-US/product/abandoned-police-department

5)

https://www.unrealengine.com/marketplace/en-US/product/scans-urban-abandoned-district-day-night-scene