Seven ball sounds like it should be similar to eight ball, but they are actually very different games. Seven ball employs many of the rules, skills, and techniques that you've learned to date, plus a few surprises. Now you just need to get a handle on the rules.
The Object and the Rules
The game is played with the object balls numbered 1 through 7, and, of course, the cue ball. The object of the game is to legally pocket the 7 ball and win the game. The balls do not have a point value, you just have to keep pocketing them in rotation one by one, starting with the ball with the lowest numerical value — so in this case, you'd start off by pocketing the 1 ball.
You either have to pocket a ball on your turn or you must at least send the cue ball or an object ball into a cushion. If you don't do one or the other, you will have committed a foul. The longer you continue to legally pocket the object balls, the longer you will keep your turn at the table. You keep going until you fail to pocket a ball legally or make a legal hit but don't pocket a ball — at that point you lose your turn to your opponent.
Now here's one of the surprises. The balls in seven ball are racked with a circular rack. If you don't own a circular rack, or you can't find one in a poolroom, you can use a nine-ball rack (diamond shape). Turn a diamond rack sideways, with one of the side points (wings) placed on the foot spot. The 1 ball is placed in the apex, or in the case of a circular rack, the 1 ball should be on the foot spot. Balls 2 through 6 should run clockwise to form the outside circle of the rack. The 7 ball should be racked in the middle.
It's traditional to lag to see who will break first. You have two choices on the break: You can either make an open break or you can pocket an object ball — you have to do one or the other for the break to be legal and to be able to continue your inning. If you don't do either one, your opponent may choose to play the table as is and strike the cue ball from behind the head string, or he or she can rerack the balls and shoot the opening break again. With each subsequent game, the loser breaks first.
Like in eight ball, if you pocket the 7 ball illegally, you lose the game.
Right after you break, your opponent chooses on which side of the table he or she will pocket the 7 ball. The rest of the balls can be pocketed anywhere on the table, but the 7 ball must be pocketed on the side of the table your opponent chooses, or the shot will be considered a foul.
If you pocket the 7 ball on a legal break, you automatically win the game.
How to Lose the Game
There are a few different ways you can lose the game, and almost all of them have something to do with that 7 ball:
You will lose the game if:
You pocket the 7 ball in one of the three pockets on your opponent's side of the table.
You pocket the 7 ball on an illegal shot.
You foul when you're shooting directly at the 7 ball. (The 7 ball must be the only ball on the table for this to occur.)
You commit three consecutive fouls.
If you pocket a ball or balls illegally, the pocketed ball(s) are spotted and your opponent takes cue-ball-in-hand anywhere on the table. If an object ball is lobbed off the table, it is spotted and the shooter is penalized with a foul.