It plays now: https://overflow.games/stillwet/?sea (or “the rising sea” from the start line). Three settlers, a villager every 8 s per town you hold, tap a town to send its people on to the next or up to the altar, seven waves that each lift the sea for good, and the score is everyone at the altar plus whoever is still standing. If you try it, tell me where it breaks or gets dull.

Fair, all of it. It is one island of about two minutes, the tribe walks a fixed path, and once you know the answer it plays the same every time. Your sketch fixes exactly that: towns that grow while you hold them, an evacuation you choose, a sea that rises with every wave, and the altar count as the score. I am building it as an endless mode on the same island and will post here when it plays. The price waits until there is something worth paying for.