Proprietary as the license permit it, i would say! 🙂 I also looked at the Maratis code, but my knowledge is small to understand it without comments. I looked at c++ a log time ago, since i was bothered with, whats this stuff “name::name, ptr->” at least i can read it. 🙂
The physics of Maratis are a little confusing since i miss the static/dynamic from the BGE engine. Maybe that should lower the physics, by setting them to static, the one you dont want to be movable, but just collidable. Yes, the optimization should be added later in development.
And some interesting articles to read:
particles-instancing, the website looks really good, dont know if you know about it.
Some useful shader stuff.