Billiards (8-ball) rules and how to shoot

Billiards (8-Ball) modes

• Practice (練習): shoot freely on your own
• Play against the CPU: choose from 3 levels, Easy, Normal or Hard (players take turns breaking)
• Random match (ランダムマッチ): find an opponent online
• Room match: play a friend using a room ID

Basic rules of Billiards (8-Ball)

• The balls are split into "solids" (1–7) and "stripes" (9–15). Your goal is to pocket every ball in your group.
• A break is legal if a ball is pocketed or at least four balls reach a cushion. Right after the break the table is open, and the group of the first ball you pocket legally becomes yours.
• If you pocket a ball from your group without a foul, you shoot again. If nothing drops, it is your opponent's turn.
• Once all your balls are down, you win by pocketing the 8-ball in the pocket you called.
• Pocketing the cue ball, hitting nothing, or hitting a ball from your opponent's group first are fouls, and your opponent may then place the cue ball anywhere.
• In online games, you have 60 seconds per shot.

How to play on Asobi Lounge

• Drag on the table to aim, then pull back the power bar and release it to shoot.
• Use "Spin" (スピン) to change where you strike the cue ball for follow, draw and side spin.
• On a computer, the left and right arrow keys fine-tune your aim angle.

How the physics works

The table is modeled as 2.54 m × 1.27 m (the playing surface of a 9-foot table) and each ball as 57.15 mm in diameter. Friction differs while a ball is sliding and while it is rolling, and a cue ball with spin moves forward (follow) or comes back (draw) after it hits an object ball.

Each shot is calculated in small steps of 1/480 of a second. The calculation uses only the four basic arithmetic operations and square roots, so the same shot gives the same result in every browser. That is why the balls never move differently on the two players' screens in online games.

How the CPU levels differ

• Easy: compares about three candidate shots before choosing, but its aim is often well off. It uses one power level and no spin.
• Normal: compares five candidates and uses two power levels plus follow and draw. It reliably makes easy shots.
• Hard: compares seven candidates, tries four power levels and spin, and even plans where the cue ball will stop after the shot. Its aim error is very small.

Shooting tips

• At first, don't hit hard. Keeping the power moderate and aiming precisely makes balls drop more often.
• Don't just pocket balls; aim to stop the cue ball where your next shot is easy. A draw shot keeps the cue ball close to you.
• When the 8-ball is the last one left, decide which pocket you will use for it first, then plan the cue ball's path.
• If only difficult shots remain, you can play a "safety": leave the cue ball where it blocks your opponent's shot.

Frequently asked questions

How is this different from 9-ball?

This site uses 8-ball rules with 15 balls. 9-ball, where you hit balls 1 to 9 in numerical order, is not available here.

Can network lag change the result of a shot?

The server decides each shot and both screens run the same calculation, so the results match.

Can I practice alone?

Yes. In "Practice" you can shoot freely with no opponent. You don't need to sign in.

Is Billiards (8-Ball) free to play?

Yes, it costs nothing. Games against the CPU and solo modes work right away without signing in. Online play (random matches and private rooms) and saving stats or leaderboard scores require signing in with a Google account. To play with a friend, your friend also needs to create an account and register as your friend.

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