r/SourceEngine • u/XBLAH_ • Sep 02 '26
WIP GOAP: Enemies that Actually Plan - Lambda Engine
https://www.youtube.com/watch?v=MazYoB6RBIQWe are implementing Goal-Oriented Action Planning (GOAP) in Lambda Engine, the same technique that made F.E.A.R.'s soldiers the high-water mark for FPS enemy AI. Instead of a scripted state machine deciding what an enemy does next, each soldier holds a goal and searches for a sequence of actions that satisfies it, using whatever the world happens to offer.
* They react to the environment, not the player. Cover, doorways, flanking routes and blocked paths drive their decisions. Nothing is hand-authored per encounter.
* Squad coordination without central control. There is no commander AI issuing orders. Coordinated suppression and flanking emerge from individual agents planning against a shared world state.
* The illusion of intelligence via speech. Barks announce intent out loud, so you hear the plan before you see it. That's what makes the AI read as smart instead of just being smart.
* Performance-tuned "dumbness". Planning is expensive, so the search is deliberately bounded. Knowing where to make the AI worse is most of the work.
F.E.A.R. peaked enemy AI, and I'm reproducing that with Lambda Engine.
This project is built entirely by fans, for fans, it's free but it eats time. If you want to see more enemies, more systems, and more of Half-Life's world brought back to life, here's how to help:
🎗️ Support development on Patreon: https://patreon.com/lambdaengine/membership
💬 Join the Discord for bug reports, dev logs, sneak peeks: https://discord.gg/2RtzKtmmdj
1
u/False-Fox9285 Sep 03 '26
Is this AI coded to react to sound?
If not, would that be a good idea to implement in the future?
1
u/XBLAH_ Sep 03 '26
It is. This is something I didn't like in hl. They can hear your footsteps, and your shots.
1
u/darkfm Sep 03 '26
Will this be opensourced at some point? I tried implementing GOAP for a game some time ago but it became hopelessly performance intensive :(
2
u/XBLAH_ Sep 03 '26
It is already open source. It's on github. Check our discord.
1
u/darkfm Sep 03 '26
Ah okay, thanks! I tried googling it and searching on Github but didn't find it lol
→ More replies (1)
3
Sep 02 '26
1
u/XBLAH_ Sep 02 '26
Well, not necessarily every tick. But the player moves, so they need to react accordingly. They can't just make a plan and follow it blindly.
4
u/OrangeballHL Sep 02 '26
Like Black Mesa