I'm at school right now so I cant try anything. As far as I remember though there isn't any gravity setting for the physics behavior. This is just off the top off my head so I'm not sure if it will work, but see if 8-direction can bump into other 8-direction objects and make them move. Also try physics objects making 8-direction move.
If they CAN make each other move (This probably isn't the best thing to do, but its the best I can think of not having C2 available)
Give each object a physics and 8-direction behavior. Then, do this:
- Object is overlapping ring
- Do Once while true
- > disable physics
- > enable 8-direction
- Object is NOT overlapping
- Do Once while true
- > enable physics
- > disable 8-direction
This way you eill probably also need to add custom controls and dont give any controls so the user won't accidently move it around while in 8-direction (unless you want them too)
Sorry if this is over complicating things, but it is the best I could think of off the top of my head.