SmartGo One vs Knight & Castle
Price, ratings, monetisation and update history for both games, side by side — with what reviewers say about each.
SmartGo One
Learn, play, and study the ancient game of Go with this comprehensive app. It offers adjustable board sizes, a powerful AI engine, interactive books, and a vast database of professional games to help you improve your skills.
- Multiple board sizes (9x9 to 19x19)
- Powerful KataGo AI engine
- Interactive Go books
- 138,000+ professional game records
- Go problems and tutorials
- Pattern matching for game analysis
- Record, annotate, and edit games
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SmartGo One is the only Go app you’ll need, whether you’re just getting started or already a seasoned player. Learn, play, study, and improve with SmartGo One. Experience the ancient game of Go on your iPhone, iPad, or Mac in a whole new way. Also known as igo (囲碁), wéiqí (围棋), or baduk (바둑), Go begins with an empty board that gradually fills as players surround territory and capture stones. Start with a 9x9 board and move up to 13x13 and 19x19 as your skills grow. SmartGo One adapts to your strength, automatically adjusting handicaps so games remain competitive and enjoyable. And when you’re ready for a serious challenge, the powerful KataGo-based engine delivers strong, rewarding play. But SmartGo One is far more than a way to play Go. Read interactive Go books while replaying the moves they describe to deepen your understanding. Explore a collection of more than 138,000 professional game records spanning both modern and historical masters. Improve your reading and decision-making skills with a growing library of Go problems and tutorials. Want to know how a master would handle a position on your board? SmartGo’s pattern matching technology compares your game with historical pro games and shows how strong players approached similar situations. No matter your level, SmartGo One helps you continue improving. Features include: • 9x9, 11x11, 13x13, and 19x19 board sizes • Powerful KataGo-based engine • Fast and responsive gameplay • Manual or automatic handicap adjustment • Record, annotate, and edit your games • Territory estimator • Hints and move analysis • Undo and replay controls • Tutorial with over 100 problems • Extensive user manual We value your privacy and only collect the minimum information necessary to make our apps work well for you. Learn more at https://smartgo.com/privacy.html. This app is licensed under Apple’s standard Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/
Knight & Castle
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Play real chess offline against Stockfish—and understand every move with clear AI feedback. Knight & Castle is a focused chess trainer for players who want a strong opponent, practical move feedback, and a clean board—without an account, matchmaking, or an internet connection. PLAY AND IMPROVE OFFLINE • Play against Stockfish from Beginner to Expert • Choose White or Black • No account or online opponent required • Practice anywhere, even without Wi-Fi or cellular data UNDERSTAND EVERY MOVE After each move, see whether it was a Best Move, Good Move, Inaccuracy, Mistake, or Blunder. Compare your move with the engine’s recommended alternative and find the moment that changed the game. Whether you are learning the rules or sharpening your strategy, Knight & Castle helps you improve at your own pace. ■ Five difficulty levels Choose Beginner, Easy, Medium, Hard, or Expert, and play as White or Black. ■ Move review & AI coach The engine grades every move you make. An on-device AI coach explains in plain language what worked, what did not, and what to focus on next. When the game ends, Game Review summarizes your accuracy, key moments, and the moves that mattered most. ■ Learning mode • Hint: see a recommended move when you are stuck • Undo: take back your last move • Move history: revisit any position • Opening names: recognize the opening you are playing • Share your game: export it as PGN ■ Made for iPhone, iPad, and iPhone Duo Play in portrait or landscape. On iPhone Duo, fold the device for a board-first view or unfold it for a larger board beside the control panel. ■ More features • Toggle board coordinates (a–h, 1–8) • Resume your game after closing the app • The chess engine runs on your device, so you can play offline The AI coach comments require a device that supports Apple Intelligence. On other devices, the engine still grades each move and shows the recommended alternative.
Screenshots
Verdict
The clearest difference is in-app purchases: Knight & Castle at none against SmartGo One's 47. SmartGo One's advantage is ads (none vs shown). On price, update cadence, device support and iOS requirement there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. SmartGo One sells 47 in-app purchases, starting at $4.99 per month. Knight & Castle asks for nothing beyond the download.
SmartGo One ships an update every 8 days, Knight & Castle weekly. The most recent releases landed on October 30, 2026 and November 1, 2026 respectively.
| Parameter | SmartGo One | Knight & Castle |
|---|---|---|
| Price | Free | Free |
| Rating | 4.8 (2K ratings) — better | — |
| Positive reviews | 76.9% of reviews | — |
| Number of ratings | 2K — better | — |
| Update frequency | Every 8 days | Weekly — better |
| Ads | No — better | Yes |
| In-app purchases | Yes | No — better |
| Monetization | Free with in-app purchases | — |
| Devices | iPhone, iPad, Mac — better | iPhone, iPad |
| Requires iOS | 26.0 | 26.0 |
| Further details — not scored | ||
| Size | 157 MB | 8 MB |
| Age rating | 4+ | +4 |
| Developer | Smart Go, Inc. | KAZUYUKI TAJIMA |
Bugs and requests
SmartGo One
Reported bugs
3 issues- Illegal move detection issues on certain board positions
- Problems with missing variations or incorrect answers
- Inconsistent behavior when passing moves
Requested features
5 requests- Add read-only mode
- Improve move suggestion explanations
- Introduce difficulty settings for AI
- Integrate online play functionality
- Provide more randomness in AI moves
Knight & Castle
Not enough reviews yet to summarise bugs or requests.
In-app purchases
SmartGo One
- SmartGo One Pro – Monthly$4.991 Month
- Pro Games and Features14 Days trial$29.991 Year
- Just Enough Japanese 1Free
- Key Concepts in Life and Death$2.99
- Go Problems Master Collection$3.99
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- Go Problems Add-on 2: Medium$3.99
- Go Problems Add-on 1: Easy$3.99
- Go Problems Add-on 3: Hard$3.99
- Counting Liberties$4.99
- The Monkey Jump$4.99
- Double Digit Kyu Games$5.99
- Go: A Complete Introduction$5.99
- How Not to Play Go$5.99
- Encyclopedia of Go Principles$5.99
- Want to Play Go? Level 1$5.99
- Black to Play 30-25 Kyu$5.99
- The Workshop Lectures 1$5.99
- Rethinking Opening Strategy$6.99
- Learn to Play Go 1$7.99
- Learn to Play Go 2$7.99
- Learn to Play Go 3$7.99
- Correct Joseki$7.99
- “The Theory of Go”$7.99
- Learn to Play Go 4$7.99
- Buddhist Philosophy Game of Go$8.99
- Graded Go Problems 1$9.99
- Graded Go Problems 2$9.99
- Want to Play Go? Level 2$9.99
- Basic Techniques of Go$9.99
- Graded Go Problems 3$9.99
- Get Strong at Life and Death$9.99
- Mastering Mini Go by Mark Tomlinson$11.99
- Fuseki Revolution$11.99
- Fundamental Principles of Go$11.99
- The Basics of Life and Death$11.99
- Joseki Revolution$11.99
- Life and Death$11.99
- A Survey of the Basic Tesujis$11.99
- Tesuji$11.99
- Tesuji for Beginners$14.99
- AlphaGo to Zero, vol. 4$14.99
- Trouble Master, volume 2$14.99
- Trouble Master, volume 1$14.99
- AlphaGo to Zero, Vol. 2$14.99
- Invincible$24.99
- Essential Go Proverbs$24.99
- Pro – Lifetime Unlock$99.00
Knight & Castle
No in-app purchases
Questions
Is SmartGo One free?
Is Knight & Castle free?
Do SmartGo One or Knight & Castle have ads?
Which is updated more often, SmartGo One or Knight & Castle?
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