# N'Back Butterfly vs Atom Shell

The clearest difference is ads: Atom Shell at none against N'Back Butterfly's shown. Atom Shell also leads on monetization model (free vs ad-supported) and iOS requirement (9.0 vs 15.6). On price, review sentiment, update cadence 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.

N'Back Butterfly ships an update every 10 months, Atom Shell every 6 months. The most recent releases landed on August 31, 2026 and September 12, 2026 respectively.

## The numbers

| Metric | N'Back Butterfly | Atom Shell |
| --- | --- | --- |
| Price | Free | Free |
| Rating | — | **[4.5 (2 ratings)](https://appshunter.io/ios/app/atom-shell/id1477722075/reviews)** |
| Number of ratings | — | **2** |
| Positive reviews | 100.0% of reviews | 100.0% of reviews |
| In-app purchases | No | No |
| Ads | Yes | **No** |
| Update frequency | Every 10 months | **Every 6 months** |
| Monetization | Ad-supported | **Free** |
| Size | 9 MB | 149 MB |
| Requires iOS | 15.6 | **9.0** |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Yasuyoshi Ota](https://appshunter.io/developer/1500357652) | [Kamran Gasimov](https://appshunter.io/developer/1458237538) |

## What reviewers say

### N'Back Butterfly

[App page](https://appshunter.io/ios/app/nback-butterfly/id853507894)

Enhance your cognitive abilities and combat forgetfulness with this application designed to improve working memory. It utilizes the scientifically recognized n-back task to train your brain's capacity for information recall and manipulation.

**Highlights:** Working memory improvement, N-back task training, Cognitive neuroscience assessment, Continuous performance task

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

**In-app purchases:** none


### Atom Shell

[App page](https://appshunter.io/ios/app/atom-shell/id1477722075)

A puzzle game where players strategically place electrons into inner shells to score points. With over 1000 levels, it offers a challenging and engaging experience for players of all ages.

**Highlights:** Electron placement mechanics, Scoring system, 1000+ levels, Intuitive gameplay

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is N'Back Butterfly free?

N'Back Butterfly is free to download, with no in-app purchases.

### Is Atom Shell free?

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

### Do N'Back Butterfly or Atom Shell have ads?

N'Back Butterfly shows ads; Atom Shell does not.

### Which is updated more often, N'Back Butterfly or Atom Shell?

N'Back Butterfly ships an update every 10 months, and Atom Shell every 6 months. Most recently, N'Back Butterfly was updated on August 31, 2026 and Atom Shell on September 12, 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.*