Each player has his own ark and wants to take as many animals on board as he can. Unfortunately, some guy called Noah claims all animal pairs for himself and has obtained an anti-pairing law. Therefore, any animal that a player has exactly twice on board at the end of the game must be discarded. However, you can circumvent the law if you manage to gather three, four or even five animals of a species.
These are considered a herd and are not only permitted, but are even more valuable. It could be so easy if it wasn't for one small issue: to form a herd, there usually is no way around getting a pair first... When the arks depart, will you win the game by having the most valuable single animals and herds on board? …