Tactical AI Kit: Alertness and Sense of Hearing

Hello Community!

I added a feature to the Tactical AI Kit that I'm quite proud of, so I decided to post an update to see what you all think.

Is it just me, or are stealth-based games becoming more and more popular? (Probably) the Quantum of Solace game, some of the Bourne Conspiracy, the sniper mission in Call of Duty 4, Metal Gear Solid 4, and the Splinter Cell series use gameplay that requires the player to avoid detection. There are also a ton of stealth game projects that some GarageGames members are hard at work on. Being a Splinter Cell addict, I personally love stealth-based games.

I came up with some ideas Saturday about how non-player characters should behave in a stealth-based game and implemented those ideas. NPCs should know how to behave when:

--they hear an enemy moving around
--they hear gunfire
--they spot a dead/dying teammate

Detecting Player Movement
When a Tactical AI Player thinks, it now does a check for objects close enough that are moving fast enough. If we detect something wrong, the NPC enters a new state that tells it to investigate the possible threat (cheating is used so they only react to enemy players, so it is technically never just a possible threat, but they act like it is). When we enter this state, we slowly walk out to where we heard the player, have a quick look around, then walk back to where we were before. Players who move slowly enough (moving while crouched or prone, in my case) won't be heard, providing that vital ability to sneak up on unwary NPCs!

Hearing Gunfire
I also added a variable in the AI Player's object that determines its alertness. An alert level of 0 means the NPC isn't expecting anything out of the ordinary, and alert level 1 means we know there's danger out there and should be on the lookout. In alert level 0, the view and hearing distance is reduced. This is a good alert level for a typical patrol or guard, as it is unrealistic to have a player that must be ALWAYS aware of everything. Alert level 1 is good for a sniper or assaulting squad, as they know they are going up against something and should be always on the lookout. An AI Player at alert level 0 is upgraded to alert level 1 when we hear gunfire (friendly or unfriendly, so getting into a firefight will alert everyone else), see a dead teammate, see a teammate with an alert level of 1, or come under fire.
An alert level system adds more value to the player using silenced weapons, as they won't alert everyone when killing enemies, making it easier to win the level.
For example, a game that has a mission with a hostage situation could have a guard variation that is set to kill hostages if alerted, forcing the player to be as stealthy as possible.

Finding a Dead Teammate
If an NPC comes across a dead teammate, they will raise their alert level and react as they would to gunfire (taking cover if we have an idea of where the threat is). Pretty simple, but all of these features combined can create some pretty interesting situations; if you snipe an enemy in the head, whoever finds the body can alert everyone else, making it realistically more difficult to make kills as everyone is taking cover and looking for any sign of movement--the next shot could give away your position!

Thanks to everyone who is reading my blog posts! BTW, just because I know somebody is going to ask this, we can expect a release hopefully in mid '09.

Video!
www.youtube.com/watch?v=IlAQPmrU2UU

Rate and comment this or I'll send my AI Players to find you...