jamespetts/monsterbreeder

Monster Breeder is a browser based strategy and simulation game built around one continuously interbreeding population of monsters that you raise to defend a kingdom's treasure. Each season alternates between two phases: a management phase where you inspect your monsters, choose which ones to breed together, allocate food, review injuries and family history, and decide who to deploy, and a raid phase where monsters, adventurers, and wildlife act on their own across a procedurally generated map while you capture, recall, or release monsters as needed. The core idea is that monsters are not fixed collectible species. Instead, every monster's colour, metabolism, body shape, behaviour, senses, and reproduction come from a genetic simulation with inheritance, mutation, dominant and codominant traits, and crossover between parents. Breeding choices shape both the individual offspring and the long-term health of the whole population. The game also tracks nutrition, fat reserves, injuries, disease, fatigue, and heat stress over time, and the terrain, climate, and biomes are procedurally generated for each world. There are several ways to play: a guided tutorial, a persistent 25 round campaign, a 20 round advanced campaign with extra setup options, a quick standalone game, and a fully custom game where you choose the seed, map size, biome, and starting treasure. The interface supports both mouse and touch, with keyboard shortcuts for actions like capturing or releasing monsters, pausing, fast forwarding, and opening the scoreboard. Technically, the whole game lives in a single main HTML file with the simulation running inside a Web Worker, so the browser's main thread only handles rendering and input. You can run it by simply opening index.html in a modern browser, or by serving the folder over a local web server, for example with Python's built in HTTP server, if the browser blocks certain features when opening the file directly. No build step is needed. Saved games and leaderboards live in the browser locally, and individual monsters can be exported and imported as JSON files to move them between games or keep long term backups. The project is under active development, so features, balance, and save compatibility may still change, and the author asks that backups be kept before updating. The code is licensed under GPL-3.0-only, and contributions such as bug reports and focused pull requests are welcome.