Geohash Card Game
The basic aim is to determine the values of two cards set aside at the start of the game. They represent the target long and lat. This pair of cards has a matching pair within the remaining cards, so finding that pair through elimination is the gameplay.
- Jokers are not included in the deck.
- "Pairs" are cards of same face value (number) and colour, eg a 4 of hearts and 4 of diamonds.
After two cards are set aside face down and unseen by all (representing longitude and latitude), all other cards are dealt out evenly amongst players. It is likely that some players will end up with more or fewer cards. Deck size may be adjusted (ensuring that all cards have a colour matched pair) to ensure all players are dealt equal numbers, or it can be accepted that the world isn't fair.
The players remove all pairs from their hand and discard them face down in a central heap.
 Early stages
Players in turn (starting left of the dealer, clockwise), ask any other player for a card from their hand. At this time in the game, they MUST ask for the partner of a card which they already have one of. If the asked player has the card (eg: black queen), then it is turned over to make a pair - which can now be discarded. If the askee does not have the requested card, then the asker picks (fishes) one randomly from their hand. The asker asks twice per turn (but does not have to be to the same askee).
This stage of the game may be recognised as a variant of 'Go Fish'.
 Mid game modifiers
- When any player drops down to two cards, the requirement that the asked-for card be in the askers hand is permanently dropped for all players. ANY card may now be asked for.
- If a player has only one or two cards, you cannot 'fish' from their hand. They must still surrender a card if asked for directly however, and can be forced out of the game if they lose all their cards. If they increase their cards above 2, they may be fished from again.
 End game
At any time a player may 'declare' one card (from their hand) to the whole table. Challenging all other players to prove that that card is NOT a long or lat card. They forfeit their next turn to ask this of only ONE card, so it is in fact a poor tactic (as even if they are right, they do not win). However they may declare two cards for the win (and if they are wrong, they have surrended two turns, but continue playing)
Alternatively, a player at ANY time may throw down the gauntlet to check the long and lat cards. They do not need to have either the long and lat cards in their hand. To do this, the player names the cards they believe to be the long/lat cards, and checks against the hidden cards. If wrong (either one or both), they are returned to hidden, and the player forfeits the rest of their game (epic fail!). Their cards are shuffled and dealt amongst all other players, starting with the player to their left.