Analysis Board
The Analysis Board is the heart of chessdroid — a complete interactive workspace for deep chess analysis. Play through entire games, explore alternative lines, and build a full variation tree with automatic engine analysis on every move.
Key capabilities:
- Interactive Board: Click or drag to make moves, explore variations, navigate with arrow keys
- Move Tree: All moves tracked in a navigable list — click any to jump to that position
- Variation Branching: Explore "what if" scenarios by playing alternatives at any point
- Auto-Analysis: Engine analysis runs after every move, with caching for instant results on revisited positions
- Engine Arrows: Green/yellow/red arrows on the board for 1st/2nd/3rd best lines
- Clickable Eval: Click the evaluation score in the output to load any PV into the move tree as a variation branch
- Free-Draw Arrows: Right-click drag to annotate anywhere on the board
- PGN Import/Export: Import games from any source, export your analysis to standard PGN
- Move Classification: Review games with Brilliant (!!), Precise (!), Best, Excellent, Good, Inaccuracy (?!), Mistake (?), Blunder (??)
- Game Library: Save and reload analyzed games — accuracy scores and eval graph fully restored
Use the Take Back button or press Backspace to undo moves. Navigate with Left/Right arrow keys.
View the full interface showcase →
Engine vs Engine Matches
Watch chess engines battle head-to-head with full series support, opening book integration, and automatic PGN saving.
Setting up a match:
- Click the ⚔ button in the board controls to show the Engine Match panel
- Select engines for White and Black
- Choose a time control: Fixed Depth, Time/move, or Clock (with increment)
- Set the number of games in the series and enable Auto-adjudicate if desired
- Optionally enable the opening book (Random weighted or Choose from ECO explorer)
- Click Start Match
A neutral arbiter engine (Stockfish 18) annotates evals independently of the playing engines — so evaluations in the move list are unbiased. All moves are saved to a PGN with engine names, eval, and time annotations.
Tournament Mode
Run multiple simultaneous engine matches on a live 2×2 board grid. Launch via the 🏆 button in board controls.
Setup:
- Round-robin: Select engines from the pool — all N×(N-1)/2 pairings are auto-generated
- Manual: Choose up to 4 custom engine pairings
- Set Games/match, time control, and opening book options
- Click Start Tournament
During the tournament:
- Up to 4 matches run simultaneously — overflow queues and starts as slots free
- Click any board to expand it: eval bar and move log appear on the right
- Live standings table shows Score / W / D / L / Games for each engine
- Full results and PGN auto-saved to
tournament_YYYYMMDD_HHmmss.txt on completion
Play vs Bot
Challenge an engine directly on the analysis board. Click ♞, set your target Elo and color, and play.
Elo targeting:
Set a target Elo from 1320 to 3190 using the numeric input, or pick a preset:
- Beginner — 1350 Elo
- Club — 1700 Elo
- Advanced — 2100 Elo
- Expert — 2500 Elo
Engines that support UCI_LimitStrength (e.g. Stockfish 9+) use true Elo limiting. Older engines fall back to Skill Level mapping.
During a bot game:
- Friendly mode: full analysis visible. Challenge mode: eval bar and engine lines hidden
- Board auto-flips when playing as Black
- Take Back goes back 2 moves (your move + bot's response)
- Draw detection: threefold repetition, insufficient material (KvK, K+minor vs K), 50-move rule
Click ⏹ at any time to return to free analysis mode.
Move Classification
Click Classify Moves to review an entire game. Each move gets a quality label displayed in distinct colors:
- !! Brilliant — Piece sacrifice that maintains a winning position
- ! Precise — The only move that wins or saves the position
- Best / Excellent / Good / Book — Solid moves, varying degrees of accuracy
- ?! Inaccuracy — Loses 5–10% win probability
- ? Mistake — Loses 10–20% win probability
- ?? Blunder — Loses 20%+ win probability
After classification, the game review panel shows quality counts for both sides and accuracy scores (Lichess formula). Click any count to jump to the first move of that type.
Opening Book & ECO Database
chessdroid includes a comprehensive opening book with over 1 million positions and a full ECO database for opening recognition.
- Opening name with ECO code shown instantly before the engine starts
- Grandmaster-approved book moves with popularity weights
- Book arrows drawn on the board (independent toggle from book text)
- Add your own Polyglot (.bin) books — industry standard format
Tactical Pattern Detection
Automatically detects tactical patterns in the position and explains them in the analysis output:
Forks
Pins
Skewers
Discovered Attacks
X-Ray Attacks
Deflection
Decoy
Overloading
Desperado
Double Check
Back-Rank Mate
Smothered Mate
Win/Draw/Loss Probabilities
Go beyond simple centipawn evaluations. See your actual chances to win, draw, or lose based on the engine's WDL score.
Position: W:72% D:20% L:8% (clear advantage)
Threat & Defense Analysis
Every move shows the new threats it creates and the defensive aspects it provides:
- Threats: Attacks on pieces, pins, forks, checkmate threats, promotion threats
- Defense: Protecting pieces, blocking attacks, escaping threats, king safety
- Red threat arrows drawn on the board for the opponent's active capture threats
Continuous Analysis
Enable Continuous Analysis in Settings to watch the engine search in real time. Live depth-by-depth updates stream until max depth, then the full annotated result appears.
- Enable via Settings → Continuous Analysis checkbox
- Set max depth in the same row (default 50, range 10–100)
- Clickable eval lines and explanations only appear in the final result
Depth 20–30 gives fast, solid analysis. Depth 40–50 is thorough for complex positions.
Play Style Recommendations
Choose your preferred playing style from Very Solid to Very Aggressive. When a move matches your style better than the engine's top choice, a Recommended section appears with the style-based alternative and full tactical breakdown.
Very Solid (0–20)
Solid (21–40)
Balanced (41–60)
Aggressive (61–80)
Very Aggressive (81–100)
Engine Profiles & Chessdroid Rating
Assign a display name and CCRL Elo to each engine EXE via the Profiles button in Settings. chessdroid also maintains a separate persistent rating ladder updated after every match.
- Per-engine display name and CCRL Elo — shown in match headers and standings
- Chessdroid Rating: K=32 ladder, seeded from CCRL on first game, updated after every match
- Rating and game count visible in the Profiles dialog — reset per engine independently
Themes, Piece Sets & Visual Effects
Make chessdroid look exactly the way you want.
- 6 app themes: Dark, Light, Cyberpunk, Dracula, Nord, Sepia — select in Settings → Theme
- 22 piece sets: All SVG, live hover preview in the dropdown — select in Settings → Pieces
- 16 board color presets + full RGB picker — select in the board controls dropdown
- Board effects: Gradient fill, vignette, piece glow, configurable board frame
- Sound effects: Move, capture, check, game-over, and castling (double-tap with gap)
Custom Position Editor
Build any board position from scratch. Place pieces freely to analyze tactical puzzles, study opening setups, or recreate positions from games. Load any position directly using a FEN string via the Load FEN button.
After setting up a position, make your first move and analysis starts automatically.
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