Writing Mystery Games in Vanilla JS: Interrogation Systems, Trust Trackers, and 6-Ending Medical Thrillers

AI Disclosure: This article was written with AI assistance. All games mentioned were built using AI-assisted development tools.

The Genre Nobody Talks About in Browser Games

When indie devs think "browser game," they think platformers, idle clickers, or puzzles. But look at the itch.io HTML5 top charts: narrative-driven mystery and horror games dominate. FORGOTTEN. Exorcist Candy. Short, story-heavy experiences that load in a second and stay with you for hours.

The technical question is: how do you build a narrative game without a game engine? No Unity. No Unreal. No Twine. Just an HTML file, a <script> tag, and whatever you can fit in under 20 KB.

I built two such games — Echo Chamber — An Interrogation Mystery (14 KB) and Flatline — A Medical Thriller (19 KB) — and this article breaks down the architecture: dialogue trees, trust/doubt state tracking, multi-ending logic, Web Audio heartbeat synthesis, and SVG EKG animation. All in vanilla JavaScript, no dependencies, no frameworks.