Gulp! is a simple card game, in the fashion of War. The cards describe a variety of marine life, and list the other cards that can be "eaten". The set of cards form a partial order: there are a few unique different apex predators that are eaten by nothing, and several instances of the Phytoplankton card that can be eaten - directly or indirectly - by all other cards.
Players each draw a card from the top of the deck: if one card eats the other, then the player claims both; if neither eat the other (or, rarely, both eat the other) then each chooses an additional card, with the winner of the next pair taking all yet-unclaimed cards. Most cards at the end of the deck wins.
