My AI Coding Agent Build In Numbers: Five Days, 16 Versions, 19 Games

🔍 Read the full analysis: My AI Coding Agent Build In Numbers: Five Days, 16 Versions, 19 Games on ThorstenMeyerAI.com

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Thorsten Meyer says an AI coding agent helped him build and publish Altersteilzeit, a free web app for tracking German phased retirement, in five days. His account says the project went through 16 versions and grew from a short animated film into a countdown service with 19 3D games, while Meyer supplied direction, made decisions and approved releases.

Meyer’s account, published October 13 on ThorstenMeyerAI.com, dates the work from Monday, September 28, to Friday, October 2, 2026. He says all 24 commits were co-authored by Claude Opus 5.5, which he used as a coding agent. The source does not provide an independent review of the app, its code or the agent’s role.

The app is designed for Germany’s Altersteilzeit block model, in which a person works an active phase and then takes a passive phase of equal length. Users enter a start date and choose a model from 1:1 to 5:5. The app calculates working days remaining, taking account of weekdays, public holidays in the selected German federal state and entered leave, Meyer says.

The finished product combines a daily countdown and milestones with a short narrated film, a calendar and bridge-day finder, badges, team countdowns, and games that link play to the user’s timeline. Meyer says it supports seven languages and five German dialects, with narrated audio. He describes it as a public website with legal pages, and says calculations happen in the browser without accounts, cookies or tracking.

A Real-World Test of Agent Work

The project offers a concrete example of how a developer used a coding agent across a short product cycle, from an initial concept to a deployed public app. Meyer reports work spanning interface features, browser-based 3D, translation, audio production and deployment. That breadth makes the account relevant to people evaluating whether coding agents can assist with more than isolated code-writing tasks.

At the same time, the project’s scale should not be mistaken for proof that the agent worked independently. Meyer says he set the tone and goals, chose features and voices, reviewed outputs and approved the release. His account presents the agent as part of a human-directed workflow, with product judgment and sign-off remaining with the developer.

The app also applies the idea to a specific audience: people counting down the working days in a phased-retirement arrangement. Its calendar calculations and privacy design are practical parts of the product, while the games and film turn a long wait into a more personal daily experience. Whether those features are useful to users beyond the creator is not established in the account.

From Film to Countdown App

Meyer says the project began with a request for a one-minute animated film about the working days in a German Altersteilzeit arrangement. In the block model, a worker first remains on the job during an active phase and later leaves work during a passive phase; a 4:4 arrangement, for example, means four years in each phase. The app’s countdown is built around that structure.

According to Meyer’s day-by-day account, the first day brought the film, date calculations, two game prototypes and an online release. The second added the daily view, language support and more games. On the third day, the project gained badges and a bridge-day finder, alongside a reported iPhone scrolling bug fix. Narration and sound effects followed on day four, and Meyer says he approved the release on day five before adding five German dialects.

He says the games use calendar time as their organizing rule: months and weeks shape a maze, while working days and holidays affect other game mechanics. Across the project, Meyer reports about 18,000 lines of JavaScript and Python, 15 test scripts, more than 1,800 text strings per language, 1,224 voice clips and 17 sound effects. These are figures reported by the developer, not independently verified measurements.

“The interesting part is not how much an AI agent can build, but what was still left for me to do.”

— Thorsten Meyer, describing the project

Independent Checks Remain Absent

The available source is Meyer’s own account. It does not include an independent technical audit, usage figures, user feedback or a comparison with development by a human-only team. The reported timeline, version count, commit authorship and production totals have not been independently confirmed here.

It is also not clear how much time Meyer spent directing and reviewing the agent, how the reported 16 versions were counted, or whether all features were tested across supported devices, languages and regional holiday calendars. Meyer mentions a fix for an iPhone scrolling problem, but does not provide broader compatibility results. His privacy description is a design claim; the source does not include a separate security or privacy audit.

Use and Verification Ahead

Meyer’s account describes Altersteilzeit as available as a public web app after his October 2 approval. The source does not name a later release date, planned features or a schedule for further updates. It also does not report how many people have used the app since publication.

The next useful evidence would come from the app’s performance in real use: whether its date calculations match users’ federal-state holidays and leave, how well it works across devices and languages, and whether users find the daily features and games helpful. Independent review of the code and privacy behavior would also help verify claims that the app calculates dates in the browser and does not track visitors.

Key Questions

What is Altersteilzeit?

Altersteilzeit is a German partial-retirement arrangement. In the block model described by Meyer, the person works during an active phase and then has a passive phase of equal length.

What does the app do?

Users enter a phase start date and choose a model. The app calculates remaining working days and offers a daily countdown, milestones, a narrated film, calendar tools and games linked to the timeline, according to Meyer.

How much of the app did the AI agent build?

Meyer says Claude Opus 5.5 co-authored all 24 project commits and handled work including coding, testing, translations, voice clips and deployment. He also says he set direction, made decisions and approved releases. The account does not independently measure each party’s contribution.

Is the app independently verified as private?

No independent privacy audit is included in the source. Meyer says the app has no accounts, cookies or tracking and performs calculations in the browser; those details are claims in his account.

Source: ThorstenMeyerAI.com