Tactical AI Kit: Stealth Pwnag3

I've been getting a lot of emails lately asking for a Tactical AI Kit Update. As you wish, community.

The last multiplayer demo I released was very successful. I was glad to be able to interact with everyone, answer their questions, and show them how horrible I am at deathmatches. It seemed like everyone had some good suggestions about how to improve my AI system and make it more fun.

The most frequent things I heard from other players were:
"AI is too stationary, he should move more"
"AI has terrible aim"
"Maps are too linear"
"AI is jumping off buildings"

And so, I set out to fix these flaws one at a time.

AI isn't as mobile as he should be
I've completely re-written the reaction code. They now use whatever they can to track their enemies, and will move on those clues. They will use enemy sightings by their teammates, last known enemy locations, and gunfire to figure out where they should be to intercept their target.
Word-of-mouth has become more dynamic. An NPC who comes under fire will be able to alert nearby teammates of where they think the sniper is (in implementation, teammate NPCs will accquire this information when they get close enough to the reacting NPC).
While doing this, they also have a sense of self-preservation. They will move slowly and cautiously as necessary, taking cover every so often, and always watching their surroundings.

Example: A guard is standing around in the street, and a bullet impacts the ground behind him. He did not hear the shot. Since the round landed behind him, he assumes that the bullet came from somewhere down the street ahead, and takes cover behind a car. He shouts to his friends that a sniper is somewhere down the street, they take cover and word of the sniper quickly travels from guard to guard. Guards who are close to the area where the sniper is begin to carefully advance towards it, keeping their distance and sticking to enclosed, less visible spaces. The sniper is found and abruptly killed.

AI has terrible aim
The aim accuracy of any NPC can be controlled through global variables which define the minimum and maximum aim inaccuracy. This marksmanship of an NPC depends on their stress (under fire) and movement (it's hard to aim when you're running).
One thing that was desperately needed was corrected aim. NPCs aim and fire at their target every 500ms by default. This becomes a problem for moving targets. Depending on the direction, speed, and distance of the target, NPCs can't seem to hit moving targets unless they are running straight at them.
The lead aiming code from the Killer Kork AI resource by Devans has now been implemented. It's a very clever function; it will decide how far ahead of a moving target to aim for a bullet at a given speed to intercept it. No more strafing circles around stationary NPCs anymore.

Maps are too linear
I got this complaint a LOT, and I quickly began to notice it myself. The quick, hacky AI Manager I coded for the multiplayer demo would spawn AI players at a certain distance away from the human players to keep from unfairly spawning behind one. In the linear maps, especially the Palace mission, the AI Manager would end up spawning NPCs on the other side of the map. Me and another player would clear out the vehicle entrance walkways, run through the server room, up to the roof, and then declare "okay, let's go back the way we came." Then we backtrack, clear out NPCs all the way to the lobby, turn around, and repeat. This got very boring.
Tuomas Kaukoranta very gratiously let me use some building he made, and I made some of my own, and I populated a large, open town with dozens of interiors and spawn points. I'll be including this in the next multiplayer demo if I decide to release another. This map demonstrates the reaction system incredibly well, and has made the AI more fun than ever. You now get to flank, hide, snipe, and use every building to your advantage to remove the presence of AI (the embedded video below shows me clearing out six AI Players from this map as stealthily as possible, only coming under fire for less than a second).

www.youtube.com/watch?v=QCXByYGUCtc

Suicidal AI
Many people were experiencing NPCs that just couldn't handle the pressure in the Middle East map in the multiplayer demo. This is a flaw in their wander function, which didn't check for a walking surface underneath the spot they plan to move to. If they spawn up on a rooftop and notice the body of a previous combatant, the react state kicks in. More likely than not, they will run off the top of the building. The wander function has now been fixed so that they look for other navigation nodes, rather than random positions, so they will only move if there is a good path to the position.

Leave a comment, tell me what you think!