Leviathans is a card game that is both characterised by the influence of randomness on the game as well as the skill of reading the other players. In this, it is similar to poker. It is more complicated though, since there are thousands of different cards to play with. It is a collectible card game that was originally designed and published by a specific company but as it became more and more popular – to the point of now being probably the most popular card game in the world of GRIM DEEP – it entered the public domain. New cards are now designed by a huge population of players and approved by a community project that governs the game and its rules. The cards all have a sea-related theme with mystical sea monsters, mermaids and other legendary creatures from mariner’s tales being very popular.

Leviathans is played both as a pastime as well as competitively for money. Collecting the different cards, many of which exist in different printings from different companies, is a popular hobby.