Bartok is a game of the Eights group. The object in these games is that to be the first to get rid of all your cards. There is a single discard pile and at your turn you can discard a card which matches the rank or the suit of the previous card. If you cannot or do not wish to play, you draw a card from the undealt stock and add it to your hand.
Certain card ranks may have special properties. For example
Bartok takes this a stage further by allowing the rules about special cards to be changed by the players as the game goes on. This makes the rules increasingly difficult to remember, and anyone who does not follow the rules has to draw one or more penalty cards. The most successful players will be those who are best at keeping abreast of the changes, and inventing new rules which will confuse the other players.
Detailed rules for Bartok (also called Bartog or Warthog) can be found on the following pages. Most of them are Australian, which suggests that perhaps Bartok is of Australian origin, or at least is especially popular there.