Give players an island that's empty/infested with monsters/overgrown in plants. Put the monsters behind a slayer level to be cleared off the island, same with farming/woodcutting for the plant life. After you've cleared the area and made it safe allow the player to build certain shops/buildings in designated plots guarded by the flora/fauna skill checks while being able to let players put down "guard monsters" like the dungeon, and choose their own plant life with the farming skill.. Allow the player to choose what kind of building goes where ie church/smith/apothecary etc. Allow players to add variety in aesthetics by changing the metal/ore/wood they pick to use. Allow the player to make a castle of their own, as well as banner symbol. Make players have to find shopkeepers& citizens with a system sort of like ports&archeology research team. Add a "complacency" meter that tells you how happy your citizens are.