The kick in Hacx is basically the same as the fists in Doom. Pressing fire will make the player deliver a kick to an enemy or decoration. It has a slighter higher rate of speed than Doom's fists. Picking up a 007MicroTel will make the kick have immense power throughout the whole level.
One of the strange things about a weapon like this is the fact that you can kick the enemies and decorations, while still running.
In Hacx 2.0, the kick was also added as a secondary fire action. This means that the player can deploy a kick anytime they want, with whatever weapon they are using, without switching to slot 1.