I’ve read these before but I’m reading through Joe Wintergreen’s posts commenting on Half-Life 2’s source code and one of the comments made me smile in the coding for the fast zombie’s leap

// Take him off ground so engine doesn't instantly reset FL_ONGROUND.
//
UTIL_SetOrigin( this, GetAbsOrigin() + Vector( 0 , 0 , 1 ));

Because I did the exact same thing in Snolf RB2 when taking a shot. Teleport one unit up so that you’re not on the ground any more.

https://www.joewintergreen.com/half-life-2-source-code-a-trawl/