This simple online game makes $20K/month | Starter Story

In 2020, during the early days of the pandemic, a software engineer named Alex built a simple online version of the domino game Mexican Train. He coded it in a single weekend, spent nothing on marketing, and launched it on a bare-bones site. Four years later, that single-page game—mexicantrain.com—generates $16,000 per month in ad revenue. His broader portfolio of arcade games, Dilly Dally Games, brings in roughly $20,000 per month total, with 300,000 monthly visitors and a startup cost of just $500. The entire business is run by one person.

The central thesis of this Starter Story episode is that a simple, single-player online game—built cheaply, distributed through search, and monetized entirely through programmatic display ads—can become a quiet, durable income stream. The episode is less a how-to guide and more a case study in what happens when you optimize for low overhead and organic traffic rather than virality or polish.

The game itself and why it works

Mexican Train is a classic domino game with a straightforward ruleset. Alex chose it because it was popular enough to have a built-in audience but not so saturated that he would be competing with dozens of polished, studio-backed versions. He built the first version in a weekend using standard web technologies—no game engine, no fancy graphics, just functional JavaScript and a clean interface.