TIDESONG

Swim: arrow keys or WASD (or the joystick on a touch screen)   Menu: Esc   Codex: C   Bag: B   Map: M   Fullscreen: F   Sing / Dance: arrow keys or WASD
Swim out of town into the wild to meet creatures, and off the edge of a region to reach the next one (the Map shows how the ocean fits together). Weaken them by fighting yourself or with a companion, then pick Sing / Dance and play the notes in time. Every creature has a heart song that makes it far easier to befriend, and legendaries listen to nothing else. Its Codex page has a clue. Sing as often as you like. If you black out, you wake up safe in town. Towns have a Healer (rest for free), a Shop, a Song Hall and a Tide Pool. Some regions need special gear from shops before the currents will let you in.