Checkers
Jump, capture and crown kings on an 8×8 board.
FAQ
What are the basic rules?
What does mandatory capture mean?
How do chain jumps and crowning work?
How do the levels and two player mode differ?
How to use
- Pick mode and level
Switch between the AI game and the two player board at the top, and choose easy, normal or hard. Changing either starts a fresh round at once. In the AI game you play red on the bottom and move first.
- Tap to move
Tap one of your pieces and every legal landing gets a mark, then tap a marked square to move or jump. Taps are ignored while it is the AI's turn, and the status line names the side to move.
- Mandatory capture and chains
When a capture exists you must capture, and quiet moves are refused. During a chain the same piece keeps jumping, so only its next landings respond to taps, and the turn passes once the chain is done.
- Crowning and kings
A man that reaches the far row is crowned immediately and the move ends there. Kings move one square in any diagonal direction and jump in all four, which makes them the strongest pieces in the endgame.
- Keyboard and undo
Move the cursor with the arrow keys, press Enter to select or land. Esc cancels, U undoes and N starts a new game. One undo takes back both the AI reply and your own last move.
About this tool
Checkers, also called draughts, is played on the dark squares of an 8×8 board, and each side starts with twelve men. A man slides one square diagonally forward, and it captures by jumping over an adjacent enemy piece into the empty square directly behind. When any capture exists, capturing is compulsory and quiet moves are refused. A piece that starts jumping must finish the whole chain with the same piece, and it may not stop halfway. A man reaching the far row is crowned and becomes a king, which moves and jumps in every diagonal direction. A side loses when it has no pieces left or no legal move on its turn.
This version offers a game against the computer and a two player board on the same screen. The AI ships in three strengths: easy plays random legal moves, normal searches three plies ahead. Hard searches five plies with alpha-beta pruning and a positional evaluation. Undo takes back the AI reply together with your last move, and the win and loss counters live in your browser. Every rule, from mandatory capture to chain jumps and crowning, is enforced by the engine, so the board never allows an illegal position. Nothing leaves the page, no account is needed, and the game works with a keyboard or with taps.
How it works
Checkers is one of the few classic board games that has been solved completely. In 2007 a research team announced, after nearly two decades of computation, that 8×8 draughts is a draw under perfect play. The proof combined endgame databases covering hundreds of billions of positions with forward search that pushed lines into known results. For club players the verdict says a perfect defence exists, while one careless move is still enough to lose a playable position. Mandatory capture is the rule that gives the game its character. Forced exchanges and sacrifice shots appear everywhere, and they reward exact calculation over slow maneuvering.
The engine here runs a negamax search with alpha-beta pruning. Evaluation starts from material: men score a base value and kings score more. On top come a small advance bonus, a reward for keeping the back row and a centre preference for kings. Move generation enumerates complete jump chains, and the search tries captures with the largest haul first, which improves pruning a lot. The three levels map to random play, three plies and five plies of search. A node budget keeps replies quick on modest hardware. The whole engine is written as pure functions, so automated tests can drive every rule directly.
When to use it
- First board game for kids
The rules fit in one minute, and a child can capture and crown within the first game. The easy level gives pieces away now and then, which keeps early wins coming. Parents can narrate the mandatory capture rule while playing, and the marked landings show exactly what the rules allow.
- Short breaks
A round often ends within five minutes, and the page opens straight into play with no install and no sign in. Switch levels between rounds to keep the games honest, and one quick undo rescues a misclick during a commute or a queue.
- Two players, one screen
Pass a single device back and forth and the engine referees everything, from mandatory captures to finished chains. Nobody has to remember the rules or argue about a jump, so the match stays about tactics. That makes it a solid choice for a quiet evening.
Tips & tricks
- Keep the back row intact for as long as you can, since it blocks enemy crowning.
- Before every move, check whether the reply can jump one of your pieces.
- Compare captures carefully: the longest chain is not always the one that survives.
- Push a man to the far row in the endgame, because a king changes the fight at once.
Things to watch
- Forgetting mandatory capture
Planning a quiet developing move while a capture is on the board leads to a refused move and a broken plan. Scan the whole board first. If any capture exists, calculate along the jumping lines instead, because the engine will not let you decline it.
- Emptying the back row
Push the back row forward too early and the crown row stands open, waiting for one enemy man to reach it. Keep one or two guards at home through the middlegame, especially while many exchanges are flying around the centre.
- Grabbing into a trap
A long chain looks generous, but the finishing square is often covered by an enemy piece ready to jump back. Look one step past every capture and check the landing square before you commit. Pick a shorter chain when the long one walks into a counter shot.