Stick
This page describes the Stick modifier of the particle system in Cinema 4D. On surface contact, particles slow down or adhere — snow settling on roofs, drops clinging to glass — optionally switching groups to trigger follow-up behavior.
This function has parallels to the Collide Modifier, as collisions of particles with dynamic objects can also be queried here and used for a group change, for example. At the same time, however, the behavior of the particles is changed when they come into contact with a surface. This mainly concerns the speed of the particles and how they are affected by other forces. This means that particles can literally stick to a surface. The strength of this adhesive force can be changed at any time using the Modifier, for example to allow the particles to drip off a surface with which they have previously collided.
The following video shows these effects. Particles hit a sphere, remain stuck there for a certain time, then slide off and finally lose contact with the sphere again. This behavior is achieved by the Stick Modifier in different variants, which changes the holding force of the particles on the surface over time.