# Sky Theory vs Mars Defender

The clearest difference is in-app purchases: Sky Theory at none against Mars Defender's 5. Sky Theory also leads on ads (none vs shown) and iOS requirement (7.0 vs 15.0). On price and device support there is nothing between them.

Both are free to download. Mars Defender sells 5 one-off in-app purchases. Sky Theory asks for nothing beyond the download.

## The numbers

| Metric | Sky Theory | Mars Defender |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | **No** | Yes |
| Ads | **No** | Yes |
| Update frequency | Every 21 months | — |
| Size | 265 MB | 82 MB |
| Requires iOS | **7.0** | 15.0 |
| Devices | iPhone, iPod | **iPhone, iPad, iPod** |
| Age rating | 9+ | 9+ |
| Developer | [More Mountains](https://appshunter.io/developer/1094758420) | [Valentina Prossapchuk](https://appshunter.io/developer/1895013467) |

## What reviewers say

### Sky Theory

[App page](https://appshunter.io/ios/app/sky-theory/id1094780926)

**Features:** macOS Compatibility

**In-app purchases:** none


### Mars Defender

[App page](https://appshunter.io/ios/app/mars-defender/id6762791745)

**In-app purchases (5)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Small Gold Pack | $0.99 | one-time |
| Medium Gold Pack | $1.99 | one-time |
| Remove ads | $2.99 | one-time |
| Starter Pack | $3.99 | one-time |
| Large Gold Pack | $4.99 | one-time |


## Frequently asked questions

### Is Sky Theory free?

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

### Is Mars Defender free?

Mars Defender is free to download, with in-app purchases available.

### Do Sky Theory or Mars Defender have ads?

Mars Defender shows ads; Sky Theory does not.

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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.*