Can I have an object have its own gravity just like Mario Galaxy? So I could jump from asteroid to asteroid?
there is nothing like an object with a lot of mass which "makes" gravity. You can disable the default gravity and add your own gravity forces to the body. Just calculate the gravity force ~ to 1/distance^2 of the object which should affect your body.
Possible to provide a sample?
I have tried the following after setting the global gravity to "Gravity = new Vector3(0, 0.0f, 0.0f);"
mainBox.Mass = 100.0f;
mainBox.Body.AddBodyForce(new Vector3(80, 50, 20));
mainBox.Body.ApplyGravity = true;
mainBox.Body.AddWorldForce(new Vector3(5, 5, 5));
But a simple box thats close to the mainBox doesn't move at all. When I enable global gravity they colide properly.
The force on a body is cleared for each simulation step. You can only (usefully) add forces inside a controller for the body. Thus, you should create a controller that looks at all nearby bodies, and adds a gravity force to the target body based on those nearby bodies. It must do this each time the controller is called, as new forces need to be calculated each step.