Half-Life 2

Agreed. Every time I think about this I feel like replaying it solo or on Synergy, gotta be my favorite game.

https://youtu.be/e0WqAmuSXEQ?feature=shared
Nuff said

That video isn't exactly a fair case (and, knowing Marphy, is more likely to be intentionally played up for comedic effect). The game's enemy AI has a routine to not attack the player if the player's line of sight to the enemy's head is blocked, to make gunfights more fair to the player. The function is intentional, but is just being demonstrated in a way that the developers likely didn't anticipate.

I'll give you that it wasn't intended but it still speaks to the basic nature of the AI. All of the combines in this game act like suicidal kamikazes, never acting beyond charging towards the player.

But in contrast, that same single mindedness works great in Ravenholm where all the enemies are just zombies. That and the atmosphere and pacing in that area is unmatched anywhere else in the game.

Hilarious clip