Play & Learn with Harold — AI chess coach now open to all players, no access code needed. Welcome modal with multimodal AI features showcase
Multimodal coaching — Harold fuses a proprietary chess neural network, structured knowledge graph, and LLM into a single coaching experience with move-by-move annotations
ElevenLabs v3 voice — upgraded TTS engine with fully spelled-out chess notation (knight eff three / skoczek ef trzy) for natural voice coaching in English and Polish
Anti-oscillation engine — prevents repetitive knight retreat loops (Nf3→Ng1) across all difficulty levels; opening book now enabled for casual mode
Live language switching — switch between English and Polish mid-game, Harold re-sends his message in the new language
Coach prompt caching — static system prompt enables ~75% cached token hits on supported providers (Anthropic, OpenAI, Google)
Eval bar — vertical evaluation rail next to the board showing real-time position advantage, like Lichess and Chess.com
ONNX Runtime backend — lightweight inference engine (~200 MB) replaces full PyTorch (~2 GB), enabling deployment on smaller servers with 2.5× faster CPU inference
Minor bug fixes — puzzle AI Vision stability, mobile layout improvements
v1.41— 25 March 2026
3 difficulty levels — Casual (~1500 Elo), Challenge (~2200 Elo), Master (~2700 Elo) with separate search depth, temperature sampling, and opening book settings
Create Game modal — choose side (White / Black / Random) and difficulty before starting
Lazy game start — server game created on first move, not on page load
Difficulty badge — current level shown in the evaluation panel
Leaderboard — difficulty column with sorting, difficulty shown in game replays
v1.4— 23 March 2026
Model V4 — 45M-parameter deep transformer with adaptive attention bias, nearly 5× larger neural network than V3. Trained on 2400+ Elo games, scores ~60% against Stockfish (~2700 Elo equivalent)
Latent thought tokens — the model "thinks" before committing to a move, boosting tactical accuracy without external search. Visible in the AI Thinking panel
2-ply negamax search — minimax lookahead with quiescence picks the objectively best move, overriding raw policy when search finds a better line
Learn platform (closed alpha) — AI-driven interactive course with 48 lessons, 172 board drills, piece tray exercises, and spaced repetition. Fully procedural — every session is unique
AI Coach Harold — personal tutor with voice, memory across sessions, board visualization tools, and adaptive difficulty
Puzzle AI Vision — LLM-powered tactical analysis with line visualization and candidate move trees
v1.32— 20 March 2026
AI move analysis — hover top moves to see arrows on the board, click to override AI's choice (analysis mode)
Probability bars — visual move confidence bars with gradient highlight on chosen move
PGN import — paste any PGN with headers into the editor or replay to view games
AI puzzle descriptions — LLM-generated tactical briefings for each puzzle via Gemini
Server-side game state — anti-cheat: server validates every move and determines results
Replay upgrade — new Chessground board with arrows, last-move highlighting, check indicators
v1.31— 19 March 2026
New board — smoother animations, last-move & check highlighting, legal move dots, better mobile touch
Puzzle Marathon — streak-based leaderboard, solve puzzles in a row without hints to rank
Puzzle result modal — board snapshot, rating change, solution replay on demand
Puzzles — tactical training with Lichess puzzle database, difficulty & theme filters, streak tracking, puzzle Elo
About page — project story, goals, and technical details
v1.3— 18 March 2026
Model V3 — hybrid CNN + Transformer with latent thought tokens, ~2500 Elo
2-ply lookahead — negamax search with quiescence
Security hardening — rate limit bypass fix, game result tampering prevention
v1.21— 17 March 2026
PGN notation — copy, load, and replay games in standard chess notation
Smarter Edit — Edit passes current position, Play from here opens editor
Mobile experience — tap-to-move with legal move dots, responsive board
Replay improvements — controls under board, Moves/PGN tab toggle
Better game stats — full move count, per-model win rates, time tiebreaker