KAIJU — Math Battle Arena

A browser math game: answer questions, battle kaiju, and evolve Gigarex through 22 stages.

Play

Open index.html in a modern browser, create a profile, and choose Start Battle. Choose multiplication tables, addition ranges, or a mix in the battle setup. Use the on-screen number pad or your keyboard; Enter submits, Backspace deletes, and Escape clears your answer.

Modes opens untimed practice, a 60-second challenge, and the 12-chapter campaign. Stats shows learning progress and battle history; Collection shows defeated enemies. English, Dutch, German, and Vietnamese are selectable from the home screen. Setup, mode menus, feedback, and the manual follow the selected language. Some detailed stats, hints, campaign text, and collection descriptions still use English.

Progress is saved in this browser's local storage. To move profiles, choose Change Profile → Export profiles, then import the JSON backup on the other device. Imports preserve existing profiles and number duplicate names. Personal challenge scores, campaign progress, and learning history move with profiles; the device leaderboard stays local. Exports also include unreadable originals for recovery. No account or server is required.

Develop and check

There is no build step or runtime package dependency. For a consistent local origin:

python -m http.server 8765 --bind 127.0.0.1

Visit http://127.0.0.1:8765. Opening the file directly also works for the game, but the diagnostics page needs HTTP. Keep the same origin to retain existing saves.

node tests/regressions.test.cjs

Open test-load.html through the local server to check the actual game startup.

Code map

Folder	Purpose
js/core/	Battle state, profiles, translations, generated sound
js/features/	Modes, analytics, achievements, hints, power-ups
js/ui/	Menus, mode screens, stats, collection, learning aids
js/utils/	Shared input, questions, arrays, UI helpers
css/	Game styles and effects
images/	22 evolution sprites and 24 enemy sprites
tests/	Regression checks using Node's built-in test runner
docs/	Review notes, reference guides, and development history
docs/archive/, js/legacy/, backup/	Historical material; not loaded by the game

Script order is defined in index.html: utilities, core systems, features, UI, the game engine, then integration. This project uses browser globals rather than modules.

See the review for fixes and remaining priorities. Older development documents describe earlier versions; the code and this README are the current starting point.