# Chess Lab: Arasan AI Engine — Online multiplayer & analysis

> Chess engine with multiplayer, analysis, and training modes. (iPhone/iPad app by koji ozono.)

- Source: https://appshunter.io/ios/app/chess-lab-arasan-ai-engine/id6757245101 (this page in markdown: same URL + `.md`)
- Developer: [koji ozono](https://appshunter.io/developer/1826482515)
- Category: Games, Board, Strategy
- Price: Free with in-app purchases (on sale, was $1.29)
- Age rating: 4+
- Requires: iOS 17.6 · 60 MB
- Languages: American English, Japanese
- Released: 2026-01-03
- Data updated: 2026-08-31
- Monetization: free with in-app purchases
- User reviews in markdown: https://appshunter.io/ios/app/chess-lab-arasan-ai-engine/id6757245101/reviews.md

## What is Chess Lab?

Chess Lab: Arasan AI Engine combines a world-class chess engine with a beautiful, intuitive interface. Whether you are a beginner looking to improve or an advanced player seeking serious analysis and competitive matches, this app brings everything together in one place.

▪ Play Instantly with “Web Invite”
 • No need to ask friends to download the app or create an account.
 • Generate an invite link, send it, and they can join instantly from any smartphone or PC browser.

▪ Versatile Game Modes
 • Online Multiplayer: Compete against players worldwide and climb the global leaderboards.
 • Web Invite Play: Seamless private matches via URL.
 • Offline CPU Battles: Train against the powerful Arasan AI with 40 adjustable strength levels.
 • Local 2-Player: Play face-to-face on a single device.

▪ In-Depth Analysis & Replays
 • Powered by Arasan: Built-in robust UCI engine delivers highly accurate evaluations and best-move calculations.
 • Real-Time Evaluation: Monitor the advantage bar and centipawn score/graph during your game.
 • Interactive History: Replay matches with step-by-step playback, fast-forward, and instant position jumping.
 • Visualized Insights: Automatically highlights significant evaluation drops (blunders) and color-codes long-thinking moves (Red/Yellow).
 • PGN Import: Import external game data (PGN).

▪ Premium Board Experience
 • 2.5D & 2D Views: Switch between an immersive 2.5D perspective and a classic flat board.
 • Assistive Highlights: Clearly displays legal moves, captures, and checks to help prevent mistakes.
 • Full Promotion Support: Choose Queen, Rook, Bishop, or Knight when your pawn reaches the final rank.
 • Suspend & Resume: Automatically saves unfinished games so you can continue later.
 • Tactile Feedback: Smooth animations paired with high-quality haptics for a satisfying feel.

## Key features

- Arasan AI engine for analysis
- Online multiplayer and web invite play
- Offline CPU battles with adjustable strength
- Real-time evaluation and game replays
- Interactive history and PGN import
- 2.5D and 2D board views
- Assistive move highlights

## Pricing and in-app purchases

Base price: Free.

**One-time purchases**

| Purchase | Price | Type |
| --- | --- | --- |
| Chess Lab Pro | $1.99 | one-time |


## Recent user reviews (3 of 3)

All indexed reviews: https://appshunter.io/ios/app/chess-lab-arasan-ai-engine/id6757245101/reviews.md

### 1/5 — キャスリングができない

*2026-04-11*

なんとかしてほしいです

**Developer response:** kanon_aさん、ご指摘ありがとうございます。
キャスリングに対応できていなかった点、大変申し訳ございませんでした。
最新のアップデートでキャスリングに対応いたしました。
ぜひ最新版をお試しください！

### 1/5 — 形勢判断と言っているが

*2026-03-11*

ただのコマの損得を表記しているだけでしかない
確かにコマの損得が形勢に大きく関わっているのは事実だが、次の一手でチェックメイトになる勝ち確状態でも駒損しているだけで形勢が悪い扱いになっている　逆も然り

つまり他の駒に守られているポーンをクイーンで取り、案の定クイーンを取られるだけの大損するような大悪手をしても、形成グラフはポーン取った分良い方に傾いてしまっている（勿論直後にクイーンを取られるまでのわずかな時間だけだが）
もっと言うとコマを取る、取られる以外で形勢が動かない

駒の有無、損得なんてわざわざコンピュータに任せずとも初心者でも盤面見りゃわかるので何の参考にもならない
勿論チェックメイトまで読み切ってる場合でもない限り基本駒損していると形勢も悪いのは事実だが、駒損になった原因はその数手前にあったりするわけで、駒を取られた時に初めて形勢が悪くなる現状の仕組みでは何が悪手かどうか何も分からない

**Developer response:** 詳細なレビューと具体的なご指摘をありがとうございます。  
ご指摘の内容を確認したところ、形勢グラフの評価処理に不具合があり、
本来使用されるはずのチェスエンジン評価ではなく、盤面の駒価値のみを基準とした簡易評価が使われている状態になっていました。
そのため、レビューでご指摘いただいたように、直後に大きく形勢が変わる局面やメイトが見えている局面でも、形勢グラフが実際の局面と一致しないケースが発生していました。
現在この問題の修正を進めており、今後のアップデートでチェスエンジンによる評価が正しく反映されるよう改善予定です。
貴重なご指摘をありがとうございました。

### 5/5 — なかなか良い

*2026-01-22*

安いのに結構本格的で面白いです👍

## Frequently asked questions about Chess Lab

### Does Chess Lab have ads?

Yes, Chess Lab contains advertisements. This allows the app to remain free for users to download and play.

### How can I play Chess Lab with friends?

You can play with friends using the 'Web Invite' feature. Generate a link and send it to your friend, who can then join instantly from any smartphone or PC browser without needing to download the app.

### What are the different game modes in Chess Lab?

Chess Lab offers Online Multiplayer, Web Invite Play for private matches, Offline CPU Battles against the Arasan AI with 40 strength levels, and Local 2-Player mode for face-to-face games on a single device.

### How does Chess Lab help me analyze my games?

The app uses the robust Arasan UCI engine for accurate evaluations and best-move calculations. It provides real-time advantage bar and centipawn scores, interactive replays, and automatically highlights blunders and long-thinking moves.

### Can I import games into Chess Lab?

Yes, Chess Lab supports PGN import, allowing you to bring external game data into the app for analysis and replay.

### What devices is Chess Lab available on?

Chess Lab is available on iPhone and iPad devices, indicated by its supported devices list.

### How often is Chess Lab updated?

The app was last updated on May 12, 2026, indicating a recent update. The latest version is 2.1.0.

### What is the age rating for Chess Lab?

Chess Lab has an age rating of +4, making it suitable for younger players and families.

## Version history (last 5 releases)

### 2.1.0 — 2026-05-12

- Added PGN Import Functionality
You can now import external game data (PGN) and view or analyze it within the app.

### 2.0.6 — 2026-04-23

Added castling support.

### 2.0.5 — 2026-03-21

• Fixed an issue where customers who previously purchased this app were unable to use Pro features.

### 2.0.4 — 2026-03-17

• Refined the settings screen layout for better usability.
• Optimized internal ad delivery systems for improved app stability.
• Minor bug fixes and performance improvements.

### 2.0.3 — 2026-03-17

[Update Details]
Fixed evaluation graph issues (Improved accuracy and update timing)
• Improved logic for accurate evaluation of checkmates and positional advantages.
• Real-time graph updates now reflect the AI's thinking process immediately after a move.

## Apps similar to Chess Lab

| App | Rating | Price | Category |
| --- | --- | --- | --- |
| [Simple Chess Trainer](https://appshunter.io/ios/app/simple-chess-trainer/id6766382515) | — | Free | Games |
| [Checkers with Ai](https://appshunter.io/ios/app/checkers-with-ai/id6757652650) | — | Free | Games |
| [Chess Puzzle Puzzle](https://appshunter.io/ios/app/chess-puzzle-puzzle/id6759465943) | — | Free | Games |
| [8bit Chess](https://appshunter.io/ios/app/8bit-chess/id6747295431) | 5.0 (3) | Free | Games |
| [Sea Battle with Ai](https://appshunter.io/ios/app/sea-battle-with-ai/id6771038135) | — | Free | Games |
| [Gambito Puzzles](https://appshunter.io/ios/app/gambito-puzzles/id6761285569) | — | Free | Games |

## More apps by koji ozono

- [WhisperDirect:AI Meeting Notes](https://appshunter.io/ios/app/whisperdirectai-meeting-notes/id6748595475)
- [WhisText](https://appshunter.io/ios/app/whistext/id6754094086)
- [Gomoku: Zen Five in a Row](https://appshunter.io/ios/app/gomoku-zen-five-in-a-row/id6756268340)
- [Reversi Simple:Satisfying Flip](https://appshunter.io/ios/app/reversi-simplesatisfying-flip/id6757232677)
- [Go Lab: AI Baduk KataGo Engine](https://appshunter.io/ios/app/go-lab-ai-baduk-katago-engine/id6757245003)

All apps by koji ozono: https://appshunter.io/developer/1826482515

## Related topics

[arasan](https://appshunter.io/ios/topics/arasan)

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-08-31.*