How did they do this?

This might be a rigging question, but how did they do this with the armature?
I want to create the object point to mouse effect also and I don’t know how this works
IkTractToPlacedByMouse.blend (91.1 KB)
Is there any way without armatures?

You can use mouseOverAny position, getVectTo() and alignAxisToVect to align object to a position.

Yes, that works, but if you want to stop it from rotating to face behind you need a little extra stuff.

You can use armature constraints in the game engine these days, so try and use the track to constraint with an object in the game scene. Or you can do what they did which is use an IK constraint along with restrictions of movement on the bone.