Robbers' rummy is a card game for two or more players which became popular in Germany in the early 20th century. Being derived from normal rummy, it emphasises arrangement of cards based on (generally simplified, but thereby no less challenging) card matching rules, while abandoning the notions of card discards or scoring entirely.

Robbers' rummy is played using two standard 52 card decks, and 2 to 6 wildcards (Jokers). Initially, each player is dealt 11 to 13 cards from the shuffled deck, whose remainder (the stock) is placed face-down on the table. The goal of each player is to reduce the number of cards held in hand by placing them on the table, face-up, forming melds. A meld is

either any sequence (by rank) of three or more cards of the same suit (where the King may be followed by Ace, and 2, and so on), 
or any three or four cards of equal rank, but of distinct suits. 
Any one Joker card used within a meld must be identified as one card of appropriate rank and suit.

At each turn, a player may place one or more cards from the own hand on the table, such that melds are formed (or extended). For this purpose, each player may rearrange any or all melds on the table (including, if necessary, by reassigning the identification of Joker cards); provided all cards on the table form melds eventually, in completion of the placement. All cards which were on the table, before the placement of the own cards from hand, must remain on the table.

(An essential point to recognize is that any meld consisting of four cards may be reduced to an equally regular three-card meld by removing or robbing one card, which in turn may be used to form other melds. The name Robbers' rummy reflects the characterization, by proponents of normal rummy, of such liberty in playing this game as excessive, or even offensive.)

A player at turn who was unable or disinclined to place at least one card from the own hand on the table accordingly, must draw one card from the stock into the hand. (Alternatively, a player who did place one or more own cards on the table may draw one card from the stock, or must otherwise yield to the next player right away.) After having drawn one card, the player at turn may still place any one or more cards on the table, and must then yield to the next player (without drawing another card).

The first player to place all held cards on the table has won the game.

The rules of robbers' rummy are very close to those adopted for the popular table game Rummikub, which uses sets of tiles numbered 1-13 instead of suits from a deck of cards. Rummikub has one claring omission from its rules; that is the rule that the cards on the table at the beginning of a turn must remain there at the end. Hence, if you play Rummikub, simply take all the tiles that anyone plays and you have the distinct advantage of being able to use those tiles, while everyone else does not.