You start on a tiny raft in open ocean with a harpoon, a fishing rod, and a day counter that only goes one way: toward Day 100. Daytime is the work shift. Hook floating Wood and Metal with the harpoon, fish or scoop food when you can, feed the Bonfire, and expand the raft so the next night hurts less. Night is when the ocean stops being friendly. Keep the Bonfire lit, hold the deck through raids, and treat long swims away from the fire as a bad idea while the Angler Fish is out.
Progress is mostly base-first. Higher Bonfire levels unlock tools like the Sawmill and Magnet, which calm the Wood and Metal scramble so you can sail farther. Map Radar and safer early islands open the rest of the map, then tougher islands and regions ask for better weapons and a raft that can take a rough night. The loop stays the same every run: gather, build, defend, explore, and try to last longer than last time.
