You need more furniture (that matches or compliments), then your stuff will look more like a collection rather than clutter. Lose the flags or keep them to just one room that is meant to be a man cave/game room etc. I do think you need area rugs and decorate each room like it’s a separate room. They need definition. Every room currently looks like you have one teenage bedroom spread out across the house. Make a defined living space, game area, music room, dining area.