# Protocol 4 vs Killer Sudoku

The clearest difference is ads: Killer Sudoku at none against Protocol 4's shown. Killer Sudoku also leads on update cadence (every 2 days vs every 3 months). On price, in-app purchases, device support and iOS requirement there is nothing between them.

Both are free to download. Protocol 4 sells 7 one-off in-app purchases and Killer Sudoku sells 1 one-off in-app purchase. Whichever you choose, the download price is not the number that matters.

Protocol 4 ships an update every 3 months, Killer Sudoku every 2 days. The most recent releases landed on October 8, 2026 and October 31, 2026 respectively.

## The numbers

| Metric | Protocol 4 | Killer Sudoku |
| --- | --- | --- |
| Price | Free | Free |
| Rating | — | **[5.0 (3 ratings)](https://appshunter.io/ios/app/killer-sudoku-bento/id6766061657/reviews)** |
| Number of ratings | — | **3** |
| Positive reviews | — | 100.0% of reviews |
| In-app purchases | Yes | Yes |
| Ads | Yes | **No** |
| Update frequency | Every 3 months | **Every 2 days** |
| Monetization | — | Free with in-app purchases |
| Size | 12 MB | 4 MB |
| Requires iOS | **17.0** | 18.0 |
| Devices | iPhone, iPad | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [HAKAN OZGER](https://appshunter.io/developer/1855495033) | [Claudiu Valentin Sararu](https://appshunter.io/developer/1884891322) |

## What reviewers say

### Protocol 4

[App page](https://appshunter.io/ios/app/protocol-4-code-breaker-pvp/id6755742805)

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

**In-app purchases (7)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Pocket Change | $0.99 | one-time |
| Starter Kit | $1.99 | one-time |
| Agent License | $2.99 | one-time |
| Hacker's Stash | $4.99 | one-time |
| Pro Kit | $4.99 | one-time |
| Trust Fund | $9.99 | one-time |
| Master Kit | $9.99 | one-time |


### Killer Sudoku

[App page](https://appshunter.io/ios/app/killer-sudoku-bento/id6766061657)

This app offers a unique twist on classic Sudoku by incorporating cage-summing math puzzles. It features a curated collection of puzzles with no ads or subscriptions, designed for focused gameplay on iOS devices.

**Highlights:** Cage-summing math puzzles, 100 hand-curated puzzles, Kids mode for younger learners, One-time unlock for all content, Neobrutalist sticker UI, Privacy-first design, no tracking

**Features:** Family Sharing

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Bento Pro | $3.99 | one-time |


## Frequently asked questions

### Is Protocol 4 free?

Protocol 4 is free to download, with in-app purchases available.

### Is Killer Sudoku free?

Killer Sudoku is free to download, with in-app purchases available.

### Do Protocol 4 or Killer Sudoku have ads?

Protocol 4 shows ads; Killer Sudoku does not.

### Which is updated more often, Protocol 4 or Killer Sudoku?

Protocol 4 ships an update every 3 months, and Killer Sudoku every 2 days. Most recently, Protocol 4 was updated on October 8, 2026 and Killer Sudoku on October 31, 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.*