Nineteen Games, One Countdown: My Experience With An AI Coding Agent

🔍 Read the full analysis: Nineteen Games, One Countdown: My Experience With An AI Coding Agent on ThorstenMeyerAI.com

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Thorsten Meyer says he built Altersteilzeit, a free web app for people counting the working days in a German partial-retirement schedule, with help from the AI coding agent Claude Opus 5.5. In an account published October 13, Meyer describes how an initial request for a one-minute film expanded over five days into a countdown, multilingual narration and 19 3D games, while he supplied direction, made product choices and approved releases.

The app is designed for Altersteilzeit in the block model, in which a person works during an active phase and is then released from work for a comparable passive phase. Users enter a start date and select a model from 1:1 to 5:5. The app calculates the other phase and estimates working days, taking account of weekdays, public holidays in the selected German state and leave entered by the user, Meyer writes.

That calculation feeds three main experiences: a daily countdown with milestones and a saying of the day; a short film depicting the active and passive phases; and a game in which years of the active phase become levels. The app also includes features such as calendar exports, a bridge-day finder, badges and a team countdown. Meyer says the games tie play to real calendar units, including weeks, months and working days.

Meyer reports that development ran from Monday, September 28, through Friday, October 2, 2026. The work included a mobile scrolling fix, audio and narration in multiple languages, and five German dialect options. He says Claude Opus 5.5 co-authored all 24 commits. His account describes a workflow in which he gave instructions, reviewed the agent’s plans and output, and decided what to accept before releases went live, a process that highlights the security risks of coding agents.

What Meyer Says He Kept in Human Hands

The account offers a concrete example of how a coding agent can contribute across a small software project, from programming and testing to translations, audio production and deployment. Meyer says the agent handled much of the implementation, including roughly 18,000 lines of JavaScript and Python, 15 test scripts and 1,224 voice clips. Those figures are reported by the project’s creator and have not been independently verified in the source material.

His description also points to work that was not simply delegated: the premise, tone and approval decisions. Meyer says he chose the cinematic approach, the sea as an image for time after work, the dialects, voices and legal-page contact details. For readers weighing what an AI coding agent can do, the distinction matters: the account describes an agent producing and coordinating work, with a person setting direction and making final calls—not an app built without human involvement.

The project’s privacy design is another practical point. Meyer says the app has no accounts, cookies or tracking, and calculates dates in the browser. Shared dates are placed after the hash mark in a URL, which he says is not sent to the server in a normal web request. The source describes these as design choices; it does not provide an independent privacy audit.

From One-Minute Film to Countdown

The project began with a narrowly defined request: a short animated film showing the working days in a German Altersteilzeit arrangement. In the block model, the active period comes first and the passive period follows; a 4:4 schedule, for example, pairs four years of work with four years away from work. Meyer says the idea was to make the act of counting feel more engaging.

According to his timeline, the first day brought the film, date calculations and early game prototypes. The following days added a daily view, languages, games, badges, a bridge-day tool and narration. By the fifth day, Meyer says he had reviewed the sound effects and approved the release. The published account describes the result as a public website and lists seven languages and five German dialects; it does not identify an independent evaluation of the app’s performance or uptake.

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

— Thorsten Meyer, in his October 13 account

What the Account Does Not Verify

The details available come from Meyer’s own project account. The source does not include a response from Anthropic, an independent review of Claude Opus 5.5’s contribution, or external testing of the app’s calculations, language quality, accessibility or security. The reported commit, code and audio counts are likewise not independently checked in the material provided.

It is also unclear how many people are using the public app, whether users have reported errors, or whether the service will be maintained beyond its initial release. Meyer describes the site as free and outlines its privacy approach, but the account does not provide usage data or a separate technical assessment of how the site handles all possible browser and hosting scenarios.

The App’s Next Test Is Public Use

The immediate next step is for users to try the published app and verify whether its date calculations and features work as intended for their circumstances. People using it would need to enter their own dates, leave and state-specific holiday information; the source does not say that the app replaces official employment or retirement guidance.

Meyer’s account does not announce a future release date, maintenance plan or roadmap. Any further development, fixes or expansion of languages and games remains unconfirmed. The article documents a five-day build and its creator’s review process, but longer-term reliability and adoption have yet to be established.

Key Questions

What is Altersteilzeit?

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

What does the app calculate?

Meyer says users enter a start date and select a model from 1:1 to 5:5. The app calculates the other phase and counts working days, accounting for weekdays, selected German state holidays and entered leave.

How many games does the app include?

Meyer describes 19 3D games, with calendar time used as part of the gameplay. His article gives examples based on weeks, months, working days and public holidays.

Did the AI agent build the app without human involvement?

No. Meyer says Claude Opus 5.5 co-authored the project’s 24 commits, while he gave instructions, made decisions, reviewed outputs and approved releases. The source does not independently verify the division of work.

Does the app collect personal data?

Meyer says the app has no accounts, cookies or tracking and performs calculations in the browser. He also says shared dates are stored in the URL after the hash mark. These are the creator’s descriptions; the source does not include an independent privacy audit.

Source: ThorstenMeyerAI.com