weather it was hard to implement or not, i think this is perfect.
you kill bots by hitting their fatal spots which are areas that have their important hardware in store, the moment you cut off the power supply for a machine it stops, just like in the game.
besides, isnt it awesome that you can furthermore chop down the head of a hammer bot that almost costed you your whole run?
or kick off the body of the last robot in lava after slicing its head off clean?