What exactly does an .actor. Do?

If you mouseover it says that it makes collide and near sensors work. I was wondering if it did anything else as well. Sometimes checking this seems to make some things work =). I try to minimize my number of ‘actors’ for framerate. Should I make every object that I am going to ineract with an ‘actor’?

the radar and near sensors are physics based, so when using them a virtual, invisible collision mesh is used to check for properties. you have to make an object an actor to tell the game engine (or better the physics engine) that it should use this additional computing and check for collisions. this helps to keep the collision detection limited to the objects which really need it.

Yes, that is all that button does. But it is important as many objects don’t need to be detected, and then it is a waste of processing time to detect collision of them.