How the Human-Hunting Robots in This TweedPunk Shooter Will Find and Kill You

Illustration for article titled How the Human-Hunting Robots in This TweedPunk Shooter Will Find and Kill You

Everybody complains about artificial intelligence. It's too dumb. It's too all-knowing. What it really is is too opaque. AI design remains one of the most mysterious disciplines of video game creation. Well, if you've ever wondered about how the rules governing the allies and opponents in a video game, then a blog post regarding Sir, You Are Being Hunted got some answers for you.


Designer Tom Betts is part of the team working on the upcoming PC shooter from Big Robot, which has aristocratic British machinemen that make sport of chasing down and slaughtering human beings. Betts has posted an entry on the game's site about the various AI states players wll encounter in the game:

Wander: NPCs move between hub locations based on various internal reasoning algorithmns, sometimes they will stop for a while and rest, or even loiter on roads outside of the settlements.

Alert/Search: If an NPC hears a nearby sound, or sees either the player or another NPC from a rival faction, they will switch into this state. In this state the hunter approaches locations close to the last heard sound or last sighting, their viewcone detection increases and they will continue exploring nearby areas until they encounter an enemy or eventually get bored and return to wandering.

Combat: If a hunter sees a target and can approach to within combat range (dependent on the range of their weapon etc), they will do so. In this state NPCs will reload and move to keep in range of their target and when losing sight of the target they will attempt to round appropriate corners to track them down.

Cover: Every time an NPC is injured they have a chance of switching to a cover-seeking state (more likely as they become more heavily wounded). When in this state they abandon all combat and run to the nearest cover location (essentially calculated from a list of locations that are out of sight of the enemy that is pursuing them). Once in cover they will constantly look around themselves to spot any chasing enemy. If found and attacked they will run on to another potential safe spot. If safe for long enough they will regain their courage and return to either a combat or search state.

The post also talks about the enemy robot factions that you'll come into contact with. Details like this make me hopeful that Sir, You Are Being Hunted will have more than an awesome title and clever concept going for it.

Building Hunted's AI: Some Fundamental Elements
[Big Robot]



The point about opaqueness is well taken.

There's a very good reason that many games have the AI say out loud something related to what it is currently doing — this is vastly more enjoyable to players than when they have no idea what logic the AI is currently operating under.

Is it silly that the AI will say "He must have run off?" when they switch back to a patrol pattern and you escape? Absolutely. But it is a fair trade-off when compared to the frustration a player might experience when they have no idea if the AI is actively hunting for them, suspicious, alarmed, or in some other state, especially if stealth gameplay is fairly unforgiving (DXHR is a great example of a good AI system which is too unforgiving with its "instantly every AI is alerted when one is" alert system). Consider how in Metal Gear games guards actually are not alarmed the instant they see you; you have about 500ms before they actually enter an alarmed phase to take them out without repercussions. This is communicated to the player in a subtle manner through the exclamation mark — the guard does not actually react until it fades away.

I adore stealth gameplay; it's easily my favorite type of 3d action experience, and a good (and consistent) AI setup is the difference between a decent stealth experience and a truly outstanding one.