Artistic Services for Top-Down Airport Management Game

We're currently developing a top-down airport management game and I need an artist to establish the visual style, then produce four assets that prove it. The game is played looking straight down from above, and that's the key thing: I want true orthographic top-down, a plan view like a drone directly overhead. No perspective, no visible walls, no isometric or 2.5D tilt. A round fuel tank is drawn as a circle. Height is suggested with a consistent soft shadow, not with geometry. The four assets are a fire station, a fuel farm, a short stay car park, and a terminal roof tileset. The tileset is the main piece of work and needs proper seamless tiling — edges, corners, diagonals and triangles for the outline, plus a set of interior tiles (roof membrane, plant and ducting, vents, rooflights, solar) that mix without an obvious pattern. Everything is PNG with transparency on a square grid, 256x256 per tile, drawn north-up in one orientation only — the engine rotates and scales. If the style works there's a lot more behind it: around fifty other buildings, surface tiles, vehicles, UI icons and a splash screen. I'd rather keep one artist than have the game look like four people drew it. I have a full written brief with the exact specification, tile list and file naming in attachments. ** AI-generated artwork is not permitted. All final artwork must be created by the commissioned artist using traditional digital art/design tools. Generative AI must not be used to create, generate, or substantially modify any of the delivered assets. Please confirm that the work is entirely your own and that you can provide the layered source files.