What I Learned From Five Days, 16 Versions, And 19 Games

🔍 Read the full analysis: What I Learned From Five Days, 16 Versions, And 19 Games on ThorstenMeyerAI.com

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Thorsten Meyer says he built a free web app for people approaching partial retirement in Germany with the help of Claude Opus 5.5, an AI coding agent, over five days from September 28 to October 2. The app grew from a proposed one-minute film into a workday countdown, a narrated animation and 19 3D games, while Meyer retained responsibility for direction, design decisions and release approval.

Meyer describes the project in an account published October 13 on ThorstenMeyerAI.com. The app, called Altersteilzeit, is designed for people using Germany’s block model of partial retirement: a period of regular work followed by an equally long period away from work. Users enter a start date and choose a model from 1:1 to 5:5; the app calculates the other phase and counts working days, accounting for weekdays, state public holidays and entered leave.

The resulting tools share that date information. A daily countdown shows remaining working days, milestones and a daily saying. Users can also export milestones to a calendar, print a countdown calendar and search for bridge days—leave days that can extend a break. A short film depicts the work and time-off phases, while the games turn years and other calendar units into levels or play mechanics.

Meyer says development moved through 16 versions in five days and 24 commits co-authored by the agent. His account credits the AI with coding, testing, translation and production work, including voice clips and sound effects. Meyer says he supplied prompts and reviewed the results, choosing elements such as the humour, the film’s tone and the voices. The app is free, and he says it has no accounts, cookies or tracking, with calculations performed in the browser.

What the Five-Day Build Shows

The project offers a specific example of an AI coding agent being used across more than a single programming task. In Meyer’s account, the agent contributed to a product that combines date calculations, browser-based 3D games, localization, audio and deployment. That makes the report relevant to readers interested in how AI tools are being applied to small software projects, as well as people looking for practical ways to track partial retirement.

The account also highlights a division of work that is easy to miss in claims about automated development. Meyer says the agent produced and tested code, but a person set the brief, chose the app’s tone and content, assessed audio and approved releases. The project is therefore presented not as a fully autonomous build, but as a rapid collaboration in which human judgment remained part of production.

For prospective users, the reported privacy design may also matter: Meyer says dates are processed locally and that the app does not use accounts, cookies or tracking. Those are the developer’s descriptions; the source account does not provide an independent technical audit.

From Film Idea to Countdown App

The starting request, according to Meyer, was for a one-minute animated film about the working days left in an Altersteilzeit arrangement. In Germany’s block model, a person first works as usual for a set period and then takes an equally long release period. Meyer says he wanted the count to feel more engaging than a number on a screen.

He dates the first request to Monday, September 28, 2026, and the completed public app to Friday, October 2. His timeline says the first day brought the film, date calculations, personal date entry and early game prototypes. Later additions included multiple languages, a daily view, more games, badges, a bridge-day finder and narrated audio. The article’s title refers to five days, 16 versions and 19 games; Meyer also reports 24 co-authored commits.

Altersteilzeit is intended for a particular retirement arrangement, rather than being a general-purpose countdown for all retirement plans. The app’s calculation depends on the dates, model, state holidays and leave entered by the user.

“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’s focus

What Has Not Been Independently Checked

The development timeline, workload figures and feature descriptions come from Meyer’s own account. The source does not include an independent review of the code, a usability assessment or verification of the app’s privacy claims. It also does not report user numbers, public reception or whether users have tested the date calculations against their individual circumstances.

Meyer describes the app as counting working days after accounting for a German federal state’s public holidays and entered leave, but the account does not detail how every edge case is handled. Readers should not treat the app’s calculations as legal or employment advice based on this article alone.

Public App and Future Validation

The app is described as public and free, and Meyer’s account presents the five-day build as completed. The source does not announce a future release date, a planned feature roadmap or a formal external review. The next useful developments for readers would be documentation of how the calculations handle regional holidays and unusual work schedules, along with feedback from people using the app.

For now, the report records Meyer’s account of the build rather than an independently tested result. Whether the app’s reported privacy protections and calculations work as described remains a matter for direct technical review and user experience.

Key Questions

What is Altersteilzeit?

Altersteilzeit is a form of partial retirement in Germany. In the block model described by Meyer, a person works during an active phase and is then released from work for a corresponding passive phase.

What does the app calculate?

Users enter a start date and choose a model from 1:1 to 5:5. The app calculates the other phase and counts working days, taking weekdays, the selected German state’s public holidays and entered leave into account, according to Meyer.

What did the AI agent contribute?

Meyer says Claude Opus 5.5 assisted with coding, testing, translations, audio production and deployment. He says he set the direction, made creative and product choices, reviewed the work and approved releases.

Is the app’s privacy design independently verified?

No independent audit is described in the source. Meyer says the app has no accounts, cookies or tracking and performs calculations in the browser, but those statements have not been independently verified in the account.

Source: ThorstenMeyerAI.com