You will have a entire zone to build in so traps, lookouts and such will be a definite possibility. Depending on how many color variants of the flag there will be either 2 flags or a neutral flag that will be revealed at a later date. But there will be a max size for the fortress in the amount of floor tiles wide and long it can be and a maximum height limit for the fortress as well as rules saying there cant be any doors blocking the way to flag rooms, no parkour of course to get to the flag rooms. Things like that.