BGE: Cube parented to another cube not colliding with objects I have a cube (cube.1) parented to another cube (cube.2), and both cubes are dynamic bodies with the same properties. Both cubes have "box" collision bounds. Also, both cubes are inside a room. 


When I move cube.2 while in the game engine, it collides with the walls of the room and stops.



But cube.1, which is parented to it, does not. Why is this happening? Also, what can I do to make cube.1 collide with objects and stop moving (stop going beyond their faces)?
When you parent an object to another you implicitly declare the child to be a static object regardless if you set the physics type to dynamic. 

If you look at the behavior you say: "I do not want this object to be controlled by the physics. I want it to follow the parent."

Therefore the physics will ignore this object.

From you question I guess you assume that the parent object considers the child. But why should it? If you want to "extend" the object you need to enable Physics/Collision Bounds/Compound on both the parent and the child.


If you need the parenting in-game see EjayACER's response. It describes how to do that with the parent actuator.