Koi Pond Simulator (2D)

This top-down 2D simulator reimplements the free-swimming koi pond mechanic in flat canvas form: each colored-patch koi picks its own heading and wanders it slowly via a per-fish turn-phase oscillator, curving back toward the center whenever it nears the pond's rim, while its tail sways on a separate faster rhythm to sell the motion. Switch between morning, day and evening lighting to see the water and pond colors shift, adjust the koi count and swim speed, and watch the live readout track how many fish are swimming and how sharply they are turning on average.