Each animal owns four traits. One is its own, the trait claims more strongly than the rest, and the other three it shares around with the rest of the items.

When a visitor selects a trait, all animals holding that trait get scores. 3 points if it is that animal's own trait, one point if it is a shared one. After four selections the highest total wins.

Ties can happen. Roughly a third of the time two or more animals get the same score, so a second rule decides : the earlier you selected something, the more it counts. Your first selection counts 4 times over, the second 3, the third 2, and the last 1. That is based on the spec, where the first choice is described as the most instinctive one.

Sometimes two animals tie even on that, and a fixed running order settles those. It is just so the selections is predictable, because the same 4 selections in the same order should always pick on the same animal.