Hello there, friendly idea here not sure if it has been suggested/planned yet.
The idea is a game mode without direct progression of the normal settlement path we all take in order to unlock buildings, this mode may allow you to choose to build freely (build cost or not) without regard to Town Tier. Achievements disabled of course for balance or what not, I wont assume.
The motive is it would allow players a sandbox gameplay where you would in effect have access to all buildings from the start giving more freedom that comes with typical sandbox game-modes. Much love to devs and game thus far.