Players plan together to outmaneuver their opponents in this format, which encourages cooperation & communication. Playing Rummy Rainbow as a team can improve its social compoonline slots bingonent, which makes it a great option for bigger parties or occasions where friendship is essential. While preserving the fundamental elements that make Rummy Rainbow fun, each variation adds a unique flavor to the game. The Ascent of Rainbow Rummy. Rummy Rainbow has become increasingly popular in recent years among both casual and card game players.