Riverboat Rummy is promoted by gameaccount. You can play on their site multiplayer Gin rummy in tournaments.
The object of Riverboat Rummy is to crete sets of 3,4 or 5 cards along the lines of the pyramid (click on 2 cards to swap them), then submit those sets for points, As cards are submitted, they are replaced from the stockpile (top-right). Play continues until all the stock cards are used no more sets can be made.
A set is valid if all the cards are of same value, or are in a suited run (aces low). Jokers are wil cards. If a player cannot make a set from the cards available, they can click the stockpile to get a new card, but will incur a penalty.