Each player should be assigned Runs or Blocks at the beginning of the game. One player gets Blocks: all other players get Runs.
Runs are A-2-3-4-5-6-7-8-9-10-J-Q-K-A in suit.
Blocks are any triples or more of a particular ranked card.
Play as regular rummy, but the Block player can only play, or add to, blocks. Run players can play anything.
If you have a playable set of cards of your type, you must play it. Run players can decide whether or not to play, or add to, Blocks.
If a complete Block is formed (four cards same type), the Block player wins.
If a complete Run is formed (2-A or A-K in suit), the Run players win.
If any player plays out their hand, they win, individually.