From First Draft To 19 Games: My AI Coding Agent Project

🔍 Read the full analysis: From First Draft To 19 Games: My AI Coding Agent Project on ThorstenMeyerAI.com

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Thorsten Meyer says he built and released Altersteilzeit, a free web app for tracking German partial-retirement schedules, over five days with help from an AI coding agent. The project grew from a request for a one-minute animated film into a site with a daily countdown, a short film, 19 3D games and multilingual narration, while Meyer says he remained responsible for direction, decisions and release approval.

Meyer’s account places the first request on Monday, September 28, 2026, and the release on Friday, October 2. Altersteilzeit is a German partial-retirement arrangement; in the block model described by Meyer, a person works during an active phase and then has an equally long passive phase away from work. The app asks users for a start date and a model ranging from 1:1 to 5:5, then calculates the corresponding dates and remaining working days.

The site combines that calculation with a morning countdown, milestone list, daily saying and progress ring. It also offers a short film depicting the two phases, a bridge-day finder, calendar exports, printable calendars, badges and a team countdown. The games use the user’s calendar as part of their structure: Meyer describes, for example, a maze arranged by months and weeks and a game in which a row represents two working weeks.

Meyer says all 24 commits were co-authored by Claude Opus 5.5. He reports that the agent handled coding, testing, translation work, audio production and deployment, while he provided prompts, reviewed results and made product and editorial choices. The account lists about 18,000 lines of JavaScript and Python, 15 test scripts, 1,224 voice clips and 17 sound effects. Those figures and descriptions are reported by Meyer; the supplied account does not include independent verification or an external technical audit.

What the Five-Day Build Shows

The project offers a concrete example of how an AI coding agent can contribute across a small software product, not just generate isolated code. Meyer describes work spanning feature development, testing, localization, audio assets and deployment, with parallel agents used for translation tasks. For readers following AI-assisted software development, the account illustrates both the breadth of work assigned to an agent and the role of a human reviewer in shaping the result.

It is also a narrowly defined personal project, not evidence that every app can be built to this scope in five days. The report is written by the project’s creator and does not provide an independent assessment of code quality, accessibility, security or user uptake. Its clearest point is Meyer’s account of the division of labor: the agent produced and checked implementation work, while he set the tone, chose features and approved what went live.

The app’s privacy design may matter to users entering dates tied to their employment plans. Meyer says there are no accounts, cookies or tracking and that calculations take place in the browser. He also says shared dates are placed after the “#” in a web address, a fragment not sent to the server in a normal web request. The source does not include a separate privacy review, so those design details remain the developer’s description.

From Film Prompt to Countdown App

The original request was deliberately small: make a short animated film counting down working days in a German Altersteilzeit block model. Meyer says the idea expanded as he and the coding agent worked through successive versions. By the first evening, he says, a working site was online; later days added languages, games, badges, audio and other tools. The account describes five days of development and multiple revisions, rather than a single request producing a finished product.

Meyer says the app supports seven languages and five German dialects, with narration and voice material in 12 languages. The supplied source also says the daily view calculates working days by excluding public holidays in the user’s German federal state and leave entered by the user. It describes 19 game modes in the opening summary, although a later passage refers to the game as playable in 15 modes. The discrepancy is not explained in the account.

The reported workflow involved short instructions, a plan from the agent, implementation, tests, activity logs and deployment, followed by Meyer’s review. Some prompts were informal and in German, according to his account. He says he made choices about humor, the sea-and-freedom theme, voices, dialects and legal-page contact details, and approved the release after reviewing the sound effects.

“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

What the Account Does Not Verify

The source is Meyer’s first-person account, not an independent test of the app or a comparative study of AI coding tools. It does not report user numbers, errors found after launch, maintenance needs, development costs or how much time Meyer spent reviewing and correcting the agent’s work. The figures for code, tests, translations and generated audio are reported by the developer.

There is also an unresolved count in the description: the opening says the site includes 19 ways to play, while another passage says the game is playable in 15 modes. The account does not clarify whether those figures refer to different categories or versions. It also does not provide an external privacy or security assessment of the app’s handling of dates and shared links.

The App’s Next Public Test

The source describes the app as publicly available after its October 2 release, but does not announce a specific next feature, update date or testing milestone. The immediate open questions are whether users encounter issues after launch, how Meyer plans to maintain the site, and whether the reported game-count difference reflects a change during development.

Any later claims about adoption, reliability or time saved would need new evidence, such as user data or an independent technical review. For now, the published account documents the development process and the creator’s division of work with the agent; it does not establish how the project performs for a wider audience.

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 then spends a matching period in a passive phase away from work.

What does the app do?

It calculates remaining working days from a user’s dates and chosen schedule, then presents a daily countdown, milestones and other features. Meyer also describes a short film, calendar tools, a bridge-day finder and calendar-based games.

How much did the AI agent do?

Meyer says the agent contributed to coding, tests, translations, audio production and deployment. He says he supplied direction, chose the tone and features, reviewed the work and approved releases. The account does not independently measure the agent’s contribution or the time spent on human review.

Does the app include 19 games?

The account’s opening says there are 19 ways to play, but a later passage describes 15 modes. Meyer’s article does not explain the difference, so the exact count by category or version is unclear.

What is known about the app’s privacy?

Meyer says the app has no accounts, cookies or tracking and calculates dates in the browser. He also says shared dates appear in the URL fragment after “#”. The source does not provide an independent privacy or security review.

Source: ThorstenMeyerAI.com