I’ve been trying to wrap my head around how best to explain this one but: glitched enemies. I know I’m not 100% alone in this, between encountering it in co-op with friends and even spotting it on a Waypoint stream (more below), but I wonder if anyone else here recognises the phenomena.
It’s often in - though not unique to - horde-based games like a Left 4 Dead. After a big battle you’ll realise there’s one enemy - zombie, alien, other monster - stuck on some geometry and no longer a threat. Or in some rare (and mildly gross) cases, maybe it’s a game that renders damage to these enemies, like the Flood in Halo where you can literally disarm them and they’re no longer able to attack.
This actually came up in a recent Waypoint stream of Aliens: Fireteam Elite. After a wave of xenomorphs, one was stuck on the wall, not attacking.
Often, as in that stream, this is a brief moment of “hey, a buddy!”. Games frequently rely on a checkpointing system that means the whole wave needs defeating, so you have to Old Yeller your new friend.