Runge Kutter Particle System
This TOX allows you to write very simple GLSL code to handle force fields in TOPs. You can set both spacial and ageing limits for particles, just like in the particle SOP.
It uses the runge Kutter Method https://de.wikipedia.org/wiki/Runge-Kutta-Verfahren to calculate precise motion.
The TOX is supposed to be used in a feedback loop as shown in the demo files.