The initial goal of project MoonDust was to develop a new particle simulation system for XSI. The existing particle system, which had been in XSI since v1.0, had reached its limits. It was a monolithic system that wasn’t flexible or customizable enough (eg available events and attributes hard coded into the system).
I never had to learn the old particle system. There weren’t that many support cases about it, and MoonDust was always just around the corner. I just remember the old particles as a jumbled forest of PPGs and parameters. See for yourself…here’s some screenshots of the old particle system:
However, the scope of the project eventually grew into the development of a procedural graph system.