This is how it looks in the editor. I am not sure if all this makes sense and how it's usually done. In this setup when players bullet hits the orange button the attached event listener starts one action which activates a particle emitter, and an action that activates motors of attached Box2D revolute joints. The yellow lines are clickable, so the connections can be deleted.
And this is in game:
Of course this is just the beginning. I need to add a lot more different event listeners and actions that can modify different types of entities in the map.