Checkers takes a minute to learn, and most people learn it slightly wrong. There is one rule that changes the entire character of the game, and half the internet leaves it out.
Eight by eight, and only the dark squares are used — the light ones are decoration. Twelve pieces each, on the three rows nearest you. The board is oriented so that each player has a dark square on their bottom-left.
A piece moves one square diagonally forwards, onto an empty dark square. That's it. Men never move backwards. Not ever.
If an enemy piece sits diagonally adjacent, and the square immediately beyond it is empty, you jump over it and remove it. Land, look again — if you can jump from your new square, you jump again, in the same turn. A single move can eat three pieces.
If you can capture, you must capture.
This isn't optional, it isn't a house rule, and it isn't the game being awkward. It's the actual rule of checkers, and it transforms the game — because it means you can force your opponent's hand. Offer a piece where taking it is compulsory, and they have no choice but to take it, landing exactly where you wanted them, in front of a multi-jump that costs them three.
That's what checkers is. Without compulsory captures it's a shuffling game. With it, it's a game about setting traps and counting exchanges — and every genuinely good checkers position is a trap somebody walked into on purpose.
A great many web checkers implementations skip this, because it's fiddly to code. The one here enforces it: if a jump is available, the board simply won't let you play anything else.
Get a man to the far row and it is crowned — it becomes a king, and a king may move and jump backwards as well as forwards. Kings are worth roughly twice a man, which is why the last row of your own pieces is precious: those four squares are the wall that stops your opponent getting crowned, and you should be extremely reluctant to move them.
One detail: if your man reaches the back row during a multi-jump, the move ends there. It's crowned, but it doesn't get to carry on jumping as a king in the same turn.
You win when your opponent has no legal move — either you've taken all their pieces, or you've blocked every one of them. Being completely blocked with pieces still on the board is a genuine loss, and a satisfying way to win.
1 – Hold the back row. Those four pieces are your anti-king defence. Every one you move is a hole.
2 – Count the exchange before you take it. A free capture is very often bait. Look at what happens after you take it — because captures being compulsory means your opponent can predict your reply exactly.
3 – Push in a body, not alone. A lone man advancing gets picked off. Two pieces supporting each other diagonally are much harder to attack.
Checkers is solved. In 2007, after eighteen years of computation, the Chinook project proved that perfect play by both sides is a draw. It remains one of the largest games ever solved, and it means a perfect checkers machine can never lose. Happily, the one here is only perfect if you set it to the top level — and even then, it searches eight moves deep, not to the end of the universe.
Yes. If a jump is available you must take it — it's the real rule, and it's what makes the game interesting, because it lets you force your opponent into a position. Many casual games and websites ignore it, which turns checkers into something much duller.
Yes. That's the entire point of being crowned. A man moves and jumps only forwards; a king does both in either direction, which makes it worth roughly double.
You lose. Running out of legal moves counts as a defeat even if you still have pieces on the board — being completely blocked is a real and perfectly respectable way to lose.