Hard International checkers
Hard International checkers is a deeper alpha-beta search on the same 10×10 rules as International checkers. Depth about five plies — stronger practice, not a claim of master International strength.
Longest capture still applies. Kings still fly. Men still jump backward.
International rules against Hard
Remove every opposing piece, or leave the other side with no legal move. The game uses the standard 10×10 International draughts start: twenty men each on fifty dark squares, white to move first.
- Men step one square diagonally forward on quiet moves; captures may run forward or backward.
- When jumps are available you must capture; if several lines exist, you must take one that captures the maximum number of enemy pieces (longest capture).
- Kings fly along open diagonals and may land on any empty square beyond a taken piece.
- A man promotes to a king only when the move ends on the far rank. A capture that passes that rank and continues leaves the piece a man; it does not fly on that turn.
What the Hard International opponent searches
The Hard opponent searches with alpha-beta depth about 5. It is a capped browser engine, not a master International draughts program.
The evaluation weights men, kings, and mobility with mandatory longest capture and flying kings; only search depth changes between Easy, Medium, and Hard.
It plans further ahead than Medium on the same board, but depth stops at five plies — strong practice, not championship strength.
Calculation on fifty squares
Compare every longest line
When jumps are on, enumerate all maximum-capture sequences — including king flights that skim several men. Hard chooses among lines you should have compared yourself.
King endgame geometry
With fewer pieces, diagonal control decides the game. Hard coordinates flying kings to trap a lone man; keep your kings on supporting diagonals.
Punish quiet mistakes
Hard searches five plies without a separate quiescence engine. Quiet positional slips still matter, but forced capture lines are where depth hurts most.
International checkers difficulty levels compared
| Level | Best for | Search | Typical gap | Practice focus |
|---|---|---|---|---|
| Easy | First games on the 10×10 board | alpha-beta depth ≈ 1 | Misses longest-capture forks two plies away | Count every piece in a forced jump before you tap |
| Medium | Regular International draughts practice | alpha-beta depth ≈ 3 | Finds short tactical shots; weaker on quiet king endgames | Use backward man jumps to open flying king lines |
| Hard (this page) | Longer tactical lines on 50 squares | alpha-beta depth ≈ 5 | Still fixed depth — not FMJD-level International play | Plan long capture chains — a man crowns only if the chain ends on the far rank |
Need a refresher on the basics? Read the complete International Checkers guide and rules on Checkerso for 10×10 board rules, mandatory longest capture sequences, and flying kings.
Frequently asked questions
How deep does Hard International checkers search?
Alpha-beta depth about 5 on the International rules used on Checkerso — not an unbounded or opening-book engine.
Is Hard unbeatable on the 10×10 board?
No. It is the strongest setting offered here for International checkers, but it is still a fixed-depth browser opponent.
Does Hard use the same rules as FMJD tournament draughts?
Checkerso implements standard International movement — flying kings, backward man capture, mandatory longest capture, and promotion only when the move ends on the far rank — on the usual 10×10 start. It does not claim certification by the FMJD or any other federation, and it does not simulate every federation tie-break or time control.