Three Seals: Dojo Duel, and what one person made

I'm the solo founder of Commercium, a one-person app studio in London, and I made all of Three Seals: Dojo Duel: the game design, the card and belt system, the art direction and character rigs, and the single codebase that ships to iOS, Android and the web. I set up the RevenueCat membership and in-app purchases, localised the game into 11 languages, built the website and made the demo video from the game's own animations. I worked with Claude Code as my engineering partner throughout.

That paragraph is what I wrote in the "describe your contribution" box when I entered the game in RevenueCat's Shipaton 2026. The full write-up is on the project page on Devpost, and there is a demo video. This is the shorter, personal version.

The game

Three Seals is a small card duel. Each card has an element and a number: fire burns wood, wood soaks up water, water puts out fire, and if the elements match the higher number wins. Every card you win goes on your shelf as a seal. Three seals of one element, or one of each element in three different colours, and the duel is yours.

It is fought by karate animals in a temple at night. You bow in, the gate closes, the clock runs, and at the end both fighters bow and say "Oss!". I wanted a game you can play in two minutes on the bus, but one that still feels like a proper dojo.

What one person made

The design. Three masters with their own habits, belts from white to black and then dan ranks, three special moves, a daily duel and monthly events. Losing never takes points away.
The art. Thirteen animal avatars drawn as hand-built rigs, a wardrobe of outfits, and a scene for every clash.
The code. One codebase with no game engine, wrapped for iOS and Android and served on the web. Every duel is seeded, so the same seed plays the same match, and a test can play whole matches before each release.
The business. The whole game is free. You pay for how you look, never for how strong you are: a Dojo Membership and tokens for outfits, run through RevenueCat. Belts, masters and card power are never for sale.
The rest. Eleven languages, the store pages, the website and the video, which is rendered from the game's own characters.

What was hard

The game itself was the easy part. The hard part was making a new player understand in thirty seconds why they won. In early tests people did not know what the dots on their shelf meant, so I turned them into element tiles with empty slots for the seals still missing, and the winning three now light up one by one before the bow.

The "Oss!" was a smaller problem with a simpler answer. No free sound library had one, so it is my own voice.

Where the machine fits

I have written before about how the work is split. Three Seals is that split in practice. Claude Code wrote and tested a great deal of the code with me. What to build, what good looks like and whose name is on the release stayed where they always stay.

You can play it in a browser now, and read the whole story on Devpost.