Egyptian Ratscrew is a card game that uses all cards in one or multiple decks. There really is no limit to the number of players.
Things you need:
One or more decks of cards
Some friends to play with
Step 1: Setup
One player deals the cards clockwise or counterclockwise, passing out the cards evenly to each player. Once the cards are passed out, players will not look at their respective cards. The game is won when one player acquires all cards in the deck(s).
Step 2: Gameplay
Gameplay will begin with the player to the left or right of the dealer, depending upon whether the players want to play clockwise or counterclockwise. The player will place the card from the top of his hand in the center of the playing surface, not looking at the card at all during the placing process (i.e. the player will turn the card away from himself as he places it). Each consecutive player repeats this process until one of the following conditions occur:
(1) A “Royalty” card is placed.
A royalty card is a Jack, Queen, King, or Ace of any suit. When one of these cards is played, called a “challenge,” the next player must play a specific number of cards, based upon which royalty was played. One card is played for a Jack, two for a queen, three for a king, or four for an ace. If the player plays a royalty card before he places all of the required cards, he stops placing cards and play continues with the next player, who must follow the royalty card rules as well.
If the player places all of the required cards without placing a royalty, the challenger picks up all of the cards in the center of the playing surface and places them at the bottom of his hand. Gameplay resumes with the challenger.
(2) A “slap” condition occurs.
A slap condition is either a “double” or “sandwich.” A double occurs when a player places the same face value card as the previous card played, including any royalty cards. A sandwich occurs when a player places the same face value card as the card played two times ago, such that there is one different card between two same-value cards. Again, this includes any royalty cards. These slap conditions may be asserted by a player when he is placing cards in response to a challenge.
When a slap condition is asserted, the first player to slap the pile of cards gets to place the pile of cards at the bottom of his hand. Play resumes with the player who won the slap.
NOTE: This game is great because the slap conditions are not static, meaning players can choose what they want their slap conditions to be besides the default conditions.
Step 3: Penalties
If a player slaps the pile of cards without a slap condition being asserted or a player plays a card out of turn, that guilty player must place the card from the top of his hand at the bottom of the pile on the playing surface. Play will resume without the order being affected.
Step 4: Elimination
If a player runs out of cards, that player is "eliminated." If the player runs out of cards in the middle of a challenge (for instance if a player runs out after placing two of the required four cards for an Ace), the next player in the sequence continues the eliminated player's challenge.
A player may slap back into the game after being eliminated if a slap condition occurs. I've been eliminated and slapped back into a game only to later win.
The game ends when all players have been eliminated, leaving one person with the entire set of cards.
Step 5: Have Fun!
Just make sure you use a stable table - all the slapping may have a tendency to knock over a low quality table!