# M21 vs 数独杀

The clearest difference is in-app purchases: M21 at none against 数独杀's 1. M21 also leads on ads (none vs shown) and iOS requirement (12.0 vs 15.0). 数独杀's advantage is update cadence (every 3 days vs every 5 weeks). On price and device support there is nothing between them.

Both are free to download. 数独杀 sells 1 one-off in-app purchase. M21 asks for nothing beyond the download.

M21 ships an update every 5 weeks, 数独杀 every 3 days. The most recent releases landed on October 26, 2026 and October 30, 2026 respectively.

## The numbers

| Metric | M21 | 数独杀 |
| --- | --- | --- |
| Price | Free | Free |
| Rating | — | **[5.0 (6 ratings)](https://appshunter.io/ios/app/murdoku/id6791810457/reviews)** |
| Number of ratings | — | **6** |
| Positive reviews | — | 56.3% of reviews |
| In-app purchases | **No** | Yes |
| Ads | **No** | Yes |
| Update frequency | Every 5 weeks | **Every 3 days** |
| Monetization | — | Free with in-app purchases |
| Size | 65 MB | 120 MB |
| Requires iOS | **12.0** | 15.0 |
| Devices | iPhone, iPod | **iPhone, iPad, iPod** |
| Age rating | 9+ | 4+ |
| Developer | [广州惟为网络科技有限公司](https://appshunter.io/developer/1000338390) | [Chengdu Yztp Technology Co., Ltd](https://appshunter.io/developer/1437368208) |

## What reviewers say

### M21

[App page](https://appshunter.io/ios/app/m21-3x/id1178637217)

**In-app purchases:** none


### 数独杀

[App page](https://appshunter.io/ios/app/murdoku/id6791810457)

Solve mysteries by finding clues in pixelated crime scenes and using logic to reconstruct events. This game combines Sudoku-style deduction with narrative-driven puzzles, allowing you to place suspects and victims correctly based on case details.

**Highlights:** Pixelated crime scene investigation, Logic-based deduction puzzles, Narrative-driven case solving, Variable grid sizes for cases, Additional castle exploration puzzles

**Features:** macOS Compatibility, Vision Pro support, iPhone Duo support

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| 数独杀VIP | $0.99 | one-time |


## Frequently asked questions

### Is M21 free?

M21 is free to download, with no in-app purchases.

### Is 数独杀 free?

数独杀 is free to download, with in-app purchases available.

### Do M21 or 数独杀 have ads?

数独杀 shows ads; M21 does not.

### Which is updated more often, M21 or 数独杀?

M21 ships an update every 5 weeks, and 数独杀 every 3 days. Most recently, M21 was updated on October 26, 2026 and 数独杀 on October 30, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*