https://www.pcgamer.com/half-life-2-mod-lets-you-stomp-enemy-heads-like-super-mario/

The best Half-Life 2 singleplayer mods pull from other games. Silent Hill, Mission: Impossible, The Stanley Parable, Half-Life 1 and… Super Mario? MobilityMod's Mobility Mod for Half-Life 2 lets you dispose of enemies by bouncing on their heads—just like Nintendo's iconic Italian plumber.    

In the same way Pulse Rifle fodder vaporises enemy Combine soldiers, the Mobility Mod makes quick work of baddies by way of head bashing.