“The only game engine that tastes better slightly burned!”
It's very important to first fire up your favorite IRC client and point it to #marshmallow_h @ freenode, then simply describe what you want to work on. The engine is still currently in a state of flux, so contributors must be willing to accommodate changes.
The above also applies for non-code contributions (like documentation and such), if you're interested in brainstorming new ideas, well, that's always welcome!
The coding standard is still a work in progress, I'm currently working on normalizing the codebase. So you're best bet is to checkout recent commits, I usually normalize files I work on.
I'll write up a proper document once I settle on the style, but for now, reading the FreeBSD style guidelines will give you and idea of how I write code (albeit with a few OOP tweaks)
Maintainer/Head-Honcho: Guillermo Antonio Amaral Bastidas
More information can be found in the HACKING file.