Hi! This brief is right in my wheelhouse. Painterly, grimy, candlelit dark fantasy is what I paint. See my published cover Who Endures: The Pain Children, a stormy night scene lit only by candle and window glow, and The Bloodmonger cover in my portfolio.
For your main menu I'd paint at 3840x2160 or larger with fully separated layers (background / figure / table / candles and flames, plus a separate flame-glow and smoke pass) so it's ready to animate, in your bone, rust and dark-red palette. 100% hand-painted, no AI at any stage.
Process: 2-3 thumbnail compositions within 48 hours, then a colour comp, then the layered final PSD. Rate for the layered key art: $450-650 depending on figure count and detail, 50% upfront. Happy to quote the Steam capsule set and the character portraits as a package too.
Portfolio: https://www.artstation.com/untameddraws and https://dribbble.com/untamed-draws