Lorenz's Paai
Goal: Sail your Chola trade ship (paai is Tamil for sail) to the port marked by the red flag and the dashed gold ring.
Ports: Poompuhar (Tamil Nadu, India), Anuradhapura (Sri Lanka), Kadaram (Kedah, Malaysia) and Srivijaya (Palembang, Indonesia), stops on the Chola sea routes across the Bay of Bengal.
Winds: The wind follows the Lorenz system (σ = 10, ρ = 28, β = 8/3): its x and y set the wind's direction and strength. The system is chaotic, so the wind can't be forecast far ahead, and when it swings quickly between its two lobes, calm water turns into a squall.
Sailing: Drag the wheel round to steer and the sail dial to trim the boom (or use the arrow keys). The boat is fastest with the sail set about halfway between the bow and the wind, and stalls "in irons" if you point straight into it.