Leave off drop ceiling and paint underside of floor above flat black like those new trendy restaurants do. Use Christmas lights up there to mimic stars. Get a coke machine that serves beer or gut it and make it a gun safe. Cover walls with old barn wood or new rough cut lumber in board and batten style. Used corrugated barn roofing for wainscoting or as a room ceiling. Might mess up acoustic properties with that tin on the ceiling.
I agree on the painting it black. I’ve seen several finished basements done this way
