# Mars Book vs Project Planet Space

The clearest difference is iOS requirement: Mars Book at 9.0 against Project Planet Space's 15.0. On price, update cadence, ads and in-app purchases there is nothing between them.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

Mars Book ships an update every 13 months, Project Planet Space every 25 months. The most recent releases landed on September 10, 2026 and May 16, 2026 respectively.

## The numbers

| Metric | Mars Book | Project Planet Space |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | **Every 13 months** | Every 25 months |
| Size | 14 MB | 2 MB |
| Requires iOS | **9.0** | 15.0 |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Vixen Co.,Ltd.](https://appshunter.io/developer/536188843) | [Miroslav Hanzelka](https://appshunter.io/developer/1653768748) |

## What reviewers say

### Mars Book

[App page](https://appshunter.io/ios/app/mars-book/id1342509724)

**In-app purchases:** none


### Project Planet Space

[App page](https://appshunter.io/ios/app/project-planet-space/id6499347273)

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is Mars Book free?

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

### Is Project Planet Space free?

Project Planet Space is free to download, with no in-app purchases.

### Do Mars Book or Project Planet Space have ads?

Neither Mars Book nor Project Planet Space shows ads.

### Which is updated more often, Mars Book or Project Planet Space?

Mars Book ships an update every 13 months, and Project Planet Space every 25 months. Most recently, Mars Book was updated on September 10, 2026 and Project Planet Space on May 16, 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.*