In Ruby Rush, the players represent prospectors trying to cash in on a sudden up-cropping of rubies in the nearby landscape, while deterring the opposition.
The deck is 26 cards, and every card has a ruby value. Most of the cards are action cards that allow players to "Dig" up more cards, steal from other players, etc. Being too greedy can result in a cave-in, eliminating the player from the game. When the deck is exhausted, the remaining players total their rubies, and the highest value wins; or if all but one player is eliminated, that player wins immediately.
The skill sets involved are risk management, and to a lesser degree, card-counting and bluffing.
Game rules include a variant for 4-5 players with the addition of another set of cards with the same game play.