# Yumina Blog

> Writing from the people building Yumina, the open-source world engine for AI roleplay and AI games. Every post is also available as Markdown: add `.md` to its URL, or request it with `Accept: text/markdown`.

## Engineering

- [An AI Crazy Dave You Can Talk To in Plants vs. Zombies](https://yumina.io/blog/ai-crazy-dave-plants-vs-zombies.md): How Yumina wired a language model into the original Plants vs. Zombies engine running as WebAssembly. One HTTP call per line, a lawn snapshot in, a validated JSON reply out, eight favors the game approves in advance, a tin whose contents are fixed before you buy, and a 64 KiB notebook.
- [How We Put AI Events and Characters Inside Slay the Spire 2](https://yumina.io/blog/ai-events-and-characters-slay-the-spire-2.md): How the SpireTalk mod runs the Yumina engine inside Slay the Spire 2, gives each AI character three decisions per line, voices events and endings, and lets the game check every reward.

## Essays

- [AI Entertainment Apps That Stay Closed Will Die](https://yumina.io/blog/why-ai-roleplay-must-be-open-source.md): Why closed AI roleplay apps and AI games forget, flatten worlds into character cards, meter every message, and cannot afford the models they advertise. Memory limits of 21 platforms compared, and why Yumina's open-source engine has no cap with your own API key and 64K memory free.
- [What AI Actually Changes About Game Design](https://yumina.io/blog/ai-game-design-human-nature.md): A game designer on pain points, peak moments, disguised frustration, and the three things AI really changes in games like RTS. By the founder of Yumina.

## Optional

- [Full text of every post](https://yumina.io/blog/llms-full.txt): all posts in one Markdown file, newest first
- [RSS feed](https://yumina.io/blog/feed.xml): full-content feed
- [Yumina docs](https://docs.yumina.io/): creator docs and the world spec
- [Source code](https://github.com/lovetimo0421/yumina-oss): the engine, editor and player, AGPL-3.0