Lessons From 19 Games And Five Days Of AI-Assisted Development

🔍 Read the full analysis: Lessons From 19 Games And Five Days Of AI-Assisted Development on ThorstenMeyerAI.com

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Developer Thorsten Meyer says he built and published Altersteilzeit, a free web app for people tracking German partial-retirement schedules, in five days with an AI coding agent. The site combines a working-day countdown, a short animated film and 19 3D games; Meyer says the agent contributed to all 24 project commits, while he set direction, made decisions and approved releases.

Meyer’s account, published October 13, describes a project that began on Monday, September 28, with a request for a one-minute animated film. By Friday, October 2, he says, the result was a public website with a daily countdown, a narrated film about the user’s work and retirement phases, games, language options and planning tools. The app is intended for people using Germany’s Altersteilzeit block model, in which a period of regular work is followed by an equal period away from work.

Users enter a date marking the start of either phase and select a schedule model, from 1:1 to 5:5. The app calculates the other date and counts weekdays, subtracting public holidays for the selected German federal state and any leave entered by the user. It also offers milestone tracking, calendar exports, a printable countdown and a tool for identifying bridge days that could extend breaks.

The game collection maps real calendar time to play: for example, months and weeks structure a maze, while working days drive an email-themed game. Meyer reports that the project includes about 18,000 lines of JavaScript and Python, 15 test scripts, and more than 1,200 voice clips. He says the app has no accounts, cookies or tracking and performs its calculations in the browser; shared dates are placed after the hash mark in a web address.

What the Five-Day Build Shows

The project offers a specific account of how an AI coding agent can contribute to a small software release: not just drafting code, but assisting with testing, translation, audio production and deployment. Meyer’s description also makes clear that the short schedule depended on a person making product choices and checking the result. He says he chose the concept and tone, selected voices and dialects, reviewed the output and approved releases.

That distinction matters to readers evaluating claims about AI-assisted development. A fast build does not, by itself, establish the app’s reliability, accessibility, user adoption or the amount of human labor involved. Meyer provides a detailed account of features and work completed, but the source does not include independent testing or usage figures. The report is best read as one developer’s case study, rather than evidence that similar projects will routinely take five days.

The app’s niche purpose also gives the work practical relevance. People approaching a long, date-based transition from work may want a clear count of remaining working days and milestones. Combining that information with games and a film is Meyer’s design choice; whether those features are useful to users has not been established in the account.

From Film Request to Public App

Meyer describes the first request as a small creative task: make a short animated film counting down the working days in an Altersteilzeit schedule. In the German block model, a person works as usual during an active phase, then spends an equivalent period in a passive phase. A 4:4 schedule, for example, pairs four years of work with four years away from work.

The project expanded in stages, according to Meyer. The first day brought date calculations, two game prototypes and an online version. Later days added seven languages, a daily view, more games, badges, a bridge-day finder, narration and sound effects. On the fifth day, he approved the release and added five German dialects, bringing the reported total to seven languages and five dialects. Meyer says each of the 24 commits was co-authored by Claude Opus 5.5, used as a coding agent.

“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 collaboration

Independent Checks and Usage Data

The account does not provide independent verification of the code, test coverage, privacy behavior or calculations, and it gives no figures for visitors or user feedback. Meyer says the app calculates dates in the browser and has no tracking, but the source does not describe an external privacy or security review. It is also unclear how the site performs across devices, browsers and accessibility needs beyond the reported iPhone scrolling hotfix.

The reported development pace is Meyer’s account of this particular project. The article does not itemize how many hours he and the agent worked, the cost of the tools, or how much time went into reviewing and correcting generated material. Those details would help readers compare the five-day schedule with other development approaches.

The App’s Next Test Is Use

The app is described as publicly available, but Meyer’s account does not name a planned next release or provide a product roadmap. The next useful indicators will be whether users adopt it, whether they report errors in holiday and working-day calculations, and whether the site receives updates after real-world use. For now, the documented milestone is the five-day build and release; further performance or impact remains to be seen.

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 is then away from work during a passive phase of equal length.

What does the app calculate?

Users enter the start date of one phase and choose a schedule model. The app calculates the other date and counts working days, subtracting weekends, relevant state public holidays and entered leave, according to Meyer.

How many games does the app include?

Meyer reports 19 3D games. Their mechanics use calendar time, including weeks, months and working days.

What did the AI coding agent do?

Meyer says the agent helped with engineering, tests, translations, voice clips, sound effects and deployment. He says he supplied direction, made creative and product decisions, reviewed the work and approved releases.

Has the app been independently tested?

The source account does not report an independent technical, privacy or security audit, nor does it provide user or performance data. Those points remain unverified in the available material.

Source: ThorstenMeyerAI.com