I have worked on spring loaded bases/figures that trigger actions from the figures. Think about how Geno's spring loaded QB arm works, except add a trigger mechanism. When the trigger is hit, the action occurs. Also similiar to a mousetrap.
I had worked on a prototype DB figure that would essentially throw the receiver to the ground when they came into contact. The figures upper torso was cocked to one side by about 1/4". When the reciever figure ran into the arms of the DB, it tripped the spring mechanism and the DB's upper body would twist back to neutral. The result was that the receiver was down on the turf. The problem is that the force would also place the DB on the ground and out of commission. It also broke way to easily and eventually I lost the pieces to put "humpty dumpty back together again".
Maybe again someday.