A 3D environment concept built in Blender and additional polish in Photoshop, the house and mech are models that I kitbashed from Sketchfab and the characters are original.
https://sketchfab.com/3d-models/xyz-draft-tank-cf8aceee2ada43cdbd7d99586f19e6fd
https://sketchfab.com/3d-models/terem-e215b6fd60ca48ddabaa77373f35176c