Building A Small Countdown With AI: Five Days, Sixteen Versions

🔍 Read the full analysis: Building A Small Countdown With AI: Five Days, Sixteen Versions on ThorstenMeyerAI.com

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Developer Thorsten Meyer says he built and published a free countdown web app with the Claude Opus 5.5 coding agent in five days, from September 28 to October 2, 2026. The project began as a request for a short animated film about Altersteilzeit, Germany’s partial-retirement system, and expanded into a daily working-day countdown, a narrated film and 19 3D games; Meyer says he made the creative decisions and approved releases.

Meyer’s account, published October 13 on ThorstenMeyerAI.com, describes an app for people in the block model of Altersteilzeit. Users enter the date marking the start of either their active or passive phase and select a model from 1:1 to 5:5. The app calculates the other phase date and counts working days, excluding weekends, state public holidays and leave entered by the user.

The resulting app combines a daily countdown and milestone view with a short film about the user’s two phases and a game that maps the active years to levels. Meyer lists features including calendar exports, a printable countdown calendar, a bridge-day finder, badges and a team countdown. He describes the release as supporting seven languages and five German dialects. His account also says the project produced a narrator in 12 languages, though it does not explain how that figure relates to the language and dialect counts.

Meyer reports that all 24 commits were co-authored by Claude Opus 5.5. He says the agent wrote code, tested features, documented its work and deployed updates, while he supplied direction and reviewed decisions. The account lists roughly 18,000 lines of JavaScript and Python, 15 test scripts, 1,224 voice clips and 17 sound effects. These are figures reported by Meyer; the article does not include an independent audit of the code, testing or production process.

A Small App With a Broad Feature Set

The project offers a concrete example of how a developer says an AI coding agent can contribute to a software build: not just generating code, but also helping with testing, translations, audio production and deployment. Its significance is less about the app’s size than the range of work packed into a short schedule. Meyer describes a single project moving from a film prototype to a public web app with several connected features.

The account also makes clear that the agent did not set the product’s purpose or approve it for release. Meyer says he chose the tone, selected the sea as an image for life after work, made decisions about voices and dialects, and gave final approval. That division of labor matters to readers weighing claims about AI-assisted development: the source describes a human-directed process, not an app created and published autonomously.

The tool may be most relevant to people approaching partial retirement. The countdown is designed around the working days that remain, accounting for local holidays and personal leave rather than showing only a calendar date. Meyer says calculations take place in the browser and that the app has no accounts, cookies or tracking. Those privacy details are claims in his account, not findings from an external review.

From Film Prompt to Countdown Tool

Altersteilzeit is a German partial-retirement arrangement. In the block model described by Meyer, a person works their usual schedule during an active phase and is then released from work for a corresponding passive phase. A 4:4 model, for example, means four years in each phase. Meyer says he wanted a playful way to count down the working days associated with that schedule.

The project began on Monday, September 28, with a request for a short animated film. On the first day, Meyer says, the work expanded to include working-day calculations, personal dates and two game prototypes. He describes adding a daily view, more game modes, translations, a narrator and sound effects over the next several days. He approved the release on Friday, October 2; five German dialects were added that day, according to his account.

The games use calendar time as their structure. Meyer gives examples including a maze arranged by months and weeks, and a game in which each email represents a working day. He says the app keeps data in the browser and places dates shared in a link after the “#” in the web address, which browsers do not send to a server as part of the request.

“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 on ThorstenMeyerAI.com

Independent Checks Are Not Provided

Meyer’s article is a first-person account, and the source material does not include independent verification of the reported development timeline, commit history, code volume, test coverage, audio totals or language support. It also does not provide usage figures, user feedback or information about how the public website has performed since launch.

Some scope details are not fully reconciled in the account. It refers to 19 games in one place and describes the game as playable in 15 modes elsewhere. It reports seven languages, five German dialects and a narrator in 12 languages, but does not specify precisely which features are available in each language or how dialects are counted. The source says there are no accounts, cookies or tracking, but supplies no third-party privacy assessment.

The article identifies Claude Opus 5.5 as the coding agent but does not explain the model’s access to external services, the extent of human review for each code change or how the reported tests were designed. Those details would help readers assess what the five-day timeline measures and how much work the agent completed without intervention.

Use and Verification Remain Open

Meyer’s account records the app’s release on October 2 but does not announce a next development milestone. The source does not state whether additional features, languages or maintenance updates are planned. For now, the next evidence of the app’s reach would be information about how people use it and whether the reported browser-based calculations and privacy behavior hold up in independent review.

Readers interested in evaluating the project can distinguish the concrete details Meyer reports—such as the five-day schedule, 24 commits and feature list—from broader conclusions about AI-assisted software development. A public code repository, independent testing results or documented user feedback could clarify how the app was built and how it works beyond the author’s account.

Key Questions

What did Meyer build?

He says he released a free web app for counting down working days during the active or passive phase of Germany’s Altersteilzeit partial-retirement arrangement. It also includes a narrated film, games and calendar-related tools.

How long did the project take?

Meyer says the work ran from September 28 to October 2, 2026, a five-day period. He describes 24 commits during that development period.

What did the AI coding agent do?

According to Meyer, Claude Opus 5.5 helped write and test code, document changes, produce translations and audio, and deploy updates. Meyer says he directed the project, made product decisions and approved releases.

Does the app collect personal data?

Meyer says the app has no accounts, cookies or tracking and calculates dates in the browser. The source account does not include an independent privacy audit, so those statements have not been externally verified here.

Are all 19 games available in every language?

The source lists 19 games and reports support for seven languages and five German dialects, with a narrator in 12 languages. It does not specify the exact language coverage of every feature or explain how the language totals relate.

Source: ThorstenMeyerAI.com