Steer your pirate ship. Drag anywhere on the screen to sail, or use WASD or the arrow keys. Your cannons fire at the nearest enemy on their own, so focus on dodging.
Sea monsters, marines and rival pirates close in from every side. Ramming them or getting hit by their shots damages your hull. When your HP runs out, your ship sinks and the run is over.
Sunk enemies drop gems. Sail over them to collect EXP. Each level-up lets you pick 1 of 3 upgrades: new weapons like the harpoon, mortar, spinning anchor, fire barrel, parrot and storm call, stronger versions of the weapons you have, or boosts like speed, armour, extra projectiles and repairs. You can carry up to five weapons. Once you have five, level-ups only offer upgrades for the weapons you already have, plus the other boosts.
Every 5th level a boss appears: the Kraken, the Marine Flagship or the Phantom Galleon. Sink it to claim a treasure chest with a bonus upgrade. The seas get rougher as you level up, and the sky turns from day to storm to night.
You score points for every enemy sunk (tougher enemies are worth more), for every level-up, and big bonuses for bosses.
P or Esc pauses, M mutes, and 1–3 picks an upgrade.