HL1 NPC behaviour ramble

half life 1 introduced some fascinating NPC behaviors that are worth exploring. the game's goldsrc engine has some crazy revolutionary features. one aspect that stands out is the depth of NPC behaviors, with each group of NPCs exhibiting behaviors tailored to their role in the game. in this all-over-the-place blog, i'll focus on these behaviors, excluding some generic HL1 enemies, and anything found in expansions. (sorry, this is an anti-shocktrooper page. go “mub puh mub dit dit” somewhere else nerd)

also, this is largely unfinished. i'll add to this again at some point, just didn't want it to let it collect dust in my decaying "documents" folder like most other random crap i write about.

earth creatures:

- rats: the rats in half life 1 are perhaps the least impressive NPCs in the game. they simply wander around without reacting to the player or other NPCs. killing them is a bitch, as they can only be gibbed with grenades. i just wanted to add these guys on the list so cockroaches wouldn't be lonely

- cockroaches: I LOVE HL1 COCKROACHES!!!!!! valve put a surprising amount of effort into creating believable behaviors for these critters. they actively search for gibs (the ooey gooey remains of NPCs) to eat, and they flee from light sources like the player's flashlight or bright room lights. they also avoid larger moving entities such as scientists or the player.

xen fauna in the base game:

- barnacles: although barnacles initially seem boring and frustrating, they possess interesting AI features. it's important to note that some of these features were changed or expanded upon in half life 2. in HL1, barnacles only attach to organic surfaces, unlike their ability in the sequel to attach to any flat ceiling surface. barnacles can only eat human NPCs and ignore xen fauna. however, a cut animation shows a vortigaunt death sequence following barnacle consumption within the games files. they have a unique feeding behavior where they consume humans and store a specific number of gibs, which they later regurgitate after "digestion".

- houndeyes: when not hostile, houndeyes exhibit curiosity behaviors such as inspecting machinery and blinking lights. this is first seen in office complex, where a houndeye can be seen staring at TV static. their behaviors vary depending on group size. when alone, they remain alert for threats, while in a squad, they "sleep" with one individual acting as a lookout. the loudness of a noise determines how quickly they wake up, with quieter sounds causing slower wake-up responses. when a lookout or "squad leader" identifies danger, all squad members will wake up with the startled animation. the damage of houndeye shockwave attacks also varies based on group size, indicated by different wave colors.

- bullsquids: bullsquids are territorial creatures with a natural instinct to attack headcrabs. however, they strangely ignore houndeyes. they are attracted to the smell of gibs and have blind spots when eating or drinking, making it easier to approach them from behind. when they've eaten their fill, they temporarily ignore food sources, inspecting them without consuming. injured bullsquids avoid food and gib smells until they've healed.

- vortigaunts: as the second smartest species in xen, vortigaunts possess a range of intelligent traits. during combat, a lookout vortigaunt can call for nearby allies with a distinct sound. when injured, a vortigaunt will flee, but it may become aggressive again if the opponent turns their back. in the "flee" state, vortigaunts seek darker areas or hide behind objects, only attacking when cornered. it's worth noting that a cut feature had vortigaunts fleeing upon seeing corpses of their companions. in xen chapters, injured passive vortigaunts often flee to healing showers before engaging in combat.

- boids: boids are bat-like creatures found in xen that exhibit passive behavior. when spawned, they form flocks and select a leader. despite only appearing once in the game, they have no scripted movement patterns and naturally avoid obstacles. if the leader dies, the flock quickly disperses and reconvenes under a new leader, accompanied by startled noises. the speed at which they flap their wings is unique to their turning and acceleration.

- gonarch: the gonarch, a massive creature, demonstrates maternal behavior toward her headcrab babies. she gives birth to headcrabs in pairs, with a maximum of 20 at a time. interestingly, her acid attack doesn't harm the baby headcrabs. when the player kills the spawned headcrabs, the gonarch emits a crying sound as if mourning her young. xen trees also avoid attacking her. a cut animation shows the gonarch assuming a defensive posture to protect her babies.

cool cut environmental features:

- moss growth: during development, the level editor for half life had a timeline feature that supported the growth of moss throughout the Black Mesa facility as time passed in the game.

- alien breeding: early marketing materials hinted at a mechanic where areas would undergo "repopulation" after players left and returned. this dynamic element aimed to make the game world feel less static but may have posed challenges for playtesters.

cool cut enemies:

- kingpin: the kingpin, a repulsive creature, was designed to guard xen caves. it had animations showing it slithering and using its claws to drag itself across the ground. equipped with 360-degree vision, psionic attacks, and defenses, it was immune to missile attacks.

- mr. friendly: mr friendly was designed to “elicit a response from the innate homophobia of 14 year old boys”, apparently. its whole schtick was that it incapacitated the player by knocking gordon onto his front, causing his glasses to fall off and thus blurring the player’s vision. mr friendly would then “fatally copulate” with the player. what..!!!!! ok !!!!!!

- fast walker: the fast walker, although never fully realized beyond the concept stage, was intended to be a xen ally acting as a pet for gordon freeman. it would have followed the player, consumed gibs after combat, and acted as a lookout for approaching enemies.

i’ll make some additions to this blog soon as i have yet to discuss any human NPC behaviour yet and other xen life, plus i want to delve into the functionality of smell and sound mechanics in the game too. i love creetures