The basic goal of the game is to avoid having to pick up cards, and try to force the other players to do so. Everyone starts with 66 points - you lose one for each "bullhead" on a card you have to pick up. When one player has lost all of their points, the game will end at the end of the current round and the player with the most points left wins!
Playing the game
Everyone starts a round with 10 cards in their hand. Four cards are placed on the table to start four rows. Every player secretly chooses a card, and then all of the cards are revealed at the same time. When the cards are revealed, they are placed on the ends of rows, from lowest value played to highest, following two rules:
1. cards are always placed in ascending order. 2. cards are always placed next to the card on the board with the smallest difference between them.
As play progresses, the rows will fill up with cards - at five cards, a row is full. If someone's card would go onto a full row, that player has to pick up all of the cards in that row, and they lose as many points as there are "bullheads" on the cards (different cards are worth different amounts - more on that in a moment). The card that the person played becomes the starting point of a new row.
If someone plays a card that is lower than the numbers at the end of all of the rows, then that player must take a row of their choice, and start a new row in its place with their card.
Each card has a number of bullheads on it - this indicates how many points it is worth when it is picked up.
Cards which end in the number "5" (ex. 5, 15, 25) are worth 2 points. Cards which end in the number "0" (10, 20, 30) are worth 3 points. Cards which have double numbers (11, 22, 33) are worth 5 points. The "55" card has both a "5" and double numbers, and is worth 7 points. All other cards are worth 1 point.
End of a round
Once a round ends, if no one has lost all of their points, then a new round begins. If someone is out of points, then the game is over and whoever still has the most points is the winner.
Tactics: This ruleset changes the number of cards in play based on how many people are playing - other than that the rules are the same. The number of cards is equal to 10x the number of players plus 4 (5 players == 54 cards, 6 players == 64 cards, etc.), so every card that could be played will find its way onto the table at some point. This changes strategy some and makes paying attention to which cards are have yet to be played important.
Logic: The same as Tactics, except that at the start of the round all of the cards are placed on the table face up, and players take turns choosing cards one at a time to build their hands before the round proper starts.
Professional: Cards are played to the left OR the right, depending on which is closest in numerical value. The card that the person played becomes the starting point of a new row.