Original prompt
Write a complete, playable single-file HTML document implementing a Checkers (draughts) game with a clean, modern UI. Use an HTML5 canvas (or DOM grid) on an 8x8 board, drawn with a polished look: alternating light/dark squares, rounded piece tokens with subtle gradients/shadows, and a highlighted selected square and valid-move indicators. Rules (standard English draughts): pieces move diagonally forward one square, capture by jumping over an opponent piece to the empty square beyond (multi-jump chains allowed), and any piece reaching the far row is crowned a KING that can also move/capture backward. Enforce the rules in code: only legal moves are selectable, forced captures are required. Implement two modes: human vs human (click to move) and human vs a simple AI. Show captured-piece counts and whose turn it is via HTML overlay. Include a New Game button that resets the board AND resets all scores to 0. Style with a clean, modern look - no external assets or fonts.SCORING & PERSISTENT HIGH-SCORE BOARD (REQUIRED): The game MUST award points for gameplay actions and maintain a persistent high-score table. When a run finishes, prompt the player to enter their name/initials and record it with the score. Save the top 5 scores (name + score) to a local JSON file in the working directory (e.g. high_scores.json), and also write the latest finished run as {"initials": name, "score": number} to /tmp/alpaca_score.json (overwrite it every run) so the arcade scoreboard can pick it up automatically, load and display them on startup and on the game-over screen, and write a new entry whenever a run finishes. Scores must survive restarting the program. Every new game MUST start with the score reset to 0 - never carry over the previous game's score into the next session. Every new game MUST start with the score reset to 0 - never carry over the previous game's score into the next session. SUCCESS CRITERIA: the page must (1) render a complete 8x8 board with correct starting layout, (2) enforce legal move/capture rules including king promotion and forced captures, (3) support click-based play in at least human-vs-human mode, (4) persist a top-5 high-score table with name entry, and (5) render the initial board without any user gesture so the headless captures a non-blank frame. OUTPUT FORMAT: Respond with the COMPLETE, self-contained HTML document in ONE single ```html code block. Do NOT split the code across multiple blocks, do NOT include a thinking summary inside the block, and do NOT place any prose, explanation, or comments between the opening and closing of the code block. The entire document (doctype through </html>) must be inside one fenced code block so it can be extracted and rendered verbatim. OUTPUT REQUIREMENT: Respond with ONLY the raw, runnable source code in a single fenced code block, with the first line starting at column 0 (no leading indentation). Do not include any thinking, explanation, summary, or prose before or after the code, and keep comments inside the code minimal.