Polar Keep Captains, Penguin Team, Submarines, the North is too hazardous traveling in a ship because of the icebergs. Area unlocks can consist of, Fossil island, Archeron and perhaps missing Pengiun Colonies or sunken islands. Having an entirely new slot with individual slot scores would be the reverse of an expansion.
It would be far too possible for players to finish the new ports, since they would not have to do the first 3 up-dates. For the present problem of not being able to get the activities you want, Jagex can add in several mechanics, such as enabling more outdoorsmen per totally reset as your slot score improves, and such as new totems that are an upgrade on the first totems, demanding terracotta.
Instead of having up to 3 symbols, as players improve their slot score, say at 4k, 5k, and 6k, the variety of symbols they can have improves to 4, 5, and 6. This allows them to get better RNG chances at the outdoorsmen they want, as long as their slot keeps improving. It would allow players to encounter reduced stage areas again, players won't have already farmed all the trade goods to take advantage of the reality straight away.
The Port position, and connections can be reused. You wouldn't really be developing anything from scratch. Even the balancing is officially done for you already. Just turn it into a different theme, with the addition of snow, and figures that fit that position. Players still have to contend the present Slots for Tank Shield and scrimshaws available there.
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