500 rum is a card game I grew up playing in western Illinois on a regular basis. I have heard it called a variety of names over the years, including rummy, rum, 500 rummy, and canasta for idiots (the latter added by an avid canasta player who could never get the hang of the game). 500 rum is the most common name I've heard and is also the name Hoyle gives it. The game itself is quite simple, but is quick to play and involves a careful touch in terms of strategy. It is often considered a member of the rummy family of card games.
Number of players
Two to eight players can play. It is best with three, four, or five. Supposedly with four players one can play as partners, but I've never played that way.
A normal deck of fifty-two cards suffices for this game. The cards are ranked with king high and ace low, with everything ranked as such in between. The king, queen, and jack are worth ten, the numbered cards are worth their respective face value, and the ace is worth 15 if melded to other aces or left in the hand, but only worth 1 if melded A-2-3-etc.
Cut or play rock-paper-scissors to see who goes first. Cards are dealt one at a time, progressing to the left. Each player receives seven cards unless you are playing with two players, where each player gets thirteen cards. The rest of the deck is placed face down in the middle of the table and is called the stock; the top card of the stock is turned over and forms the beginning of the discard pile.
Goal of the game
The goal is to be the first to have an empty hand; this can happen in the middle of a turn or at the end after a discard. This is done by forming sequences of three or more of a kind, either in sequential order of the same suit or of the same face value; these are melds. Ideally, you want these sequences to have a high point value, explained above when describing "the deck."
Playing the game
The player to the left of the dealer begins, and play progresses to the left. Each player on his/her turn starts off by drawing the top card of the stock or a card from the discard pile. The discard pile is spread out in order such that each card's value and suit can be seen by everyone. If the player chooses to take a card from the discard pile (any one can be taken), that card must be used in a meld immediately, plus all cards on top of it on the pile must be added to that player's hand.
After the draw, the player can make as many melds as he or she wishes; you can also add to your own. The player signifies the end of the turn by discarding a single card to the top of the discard pile from the hand.
You may also build on your opponent's melds, if you wish. Say your opponent has a meld of 2-3-4; you may lay a single 5 in front of you as an extension of that meld. You can also play off of extensions of melds or off of the original meld; in the example above, you could play a 5 off of the original meld or a 6 off of the extension.
When the hand ends by one player emptying his/her hand, all players add up the points of the cards in front of them that they have played, then subtracts the points of all cards held in their hand. A running total of this is kept from hand to hand, and the first player to 500 wins the game. If you're a gambler, a common way of playing is when one player goes out, all other players owe that player a penny (or more) for each point below 500 that that player ends the game at. If two players go over, the one with the higher total wins, but the other player over 500 owes nothing.
The biggest element of strategy here is to not be afraid to pick up the discard pile to complete a meld. As the game progresses, it is very easy to play many cards, either by extending your own melds or the melds of others. Picking up a large number of cards will usually result in the ability to play a lot of them very quickly, providing a huge boon in points. Of course, sometimes a player does get caught with a handful of cards using this strategy, but more often than not it pays off greatly.
Another useful strategy is to focus only in making melds of cards of the same rank, making it much harder for other players to build off of you. Feel free to scavenge off of their sequential melds, but give them little opportunity to feed from you.
A common variant I've heard of is playing for only two deals, with the winner of each deal earning a bonus of 50 points. This is often played in gambling situations, though it's very fun and competitive in a one-on-one situation. Another variant keeps the aces high and makes them always worth 15 no matter what; this is more just a variant to change the flavor a touch.