Adopt a koi for 0.0005 ETH, and it swims its own slow path for three days. Adopt it again to keep it longer. Every hour food lands on the water, and the three nearest koi eat: 1%, 0.5% and 0.25% of the pot. Holders' koi are golden and notice food from twice as far away. On the third day there's a feast, with food every ten minutes for an hour. On the seventh, the koi that ate most takes what remains. Each adoption sends 80% to the pot and 20% to buying $KOI and burning it.