Ambient AI is a concept in gaming where portions of a game's software are devoted to AI with a little interactivity, being intended as background fillers to give a more realistic feel. This ranges from birds flying in the distance, to animals that run away from the player.
Resident Evil 4
In the first chapter of Resident Evil 4, a dog can be found trapped in a bear trap. Leon S. Kennedy can opt to free him via action command, whereupon it will run into the surrounding wilderness. If Leon helps the dog, during his first fight with an El Gigante the dog will reappear to distract the monster.[excerpt 1] He disappears after Leon manages to kill the El Gigante and is not seen or mentioned again in the game. The dog can be freed by shooting at the beartrap, but doing that or not helping at all will make it not help you later on. The dog also serves as warning to new players about the other bear traps up ahead.
A dog can be found in the Farm area of the Village in Resident Evil 4. It will run up and bark at Leon, but will then run away scared if it is approached or shot at. According to the biohazard 4 kaitaishinsho guide, it was bred and raised on the farm. It was only programmed to bark and run away, and cannot be killed by any weapon.[excerpt 2]
In the first chapter of Separate Ways, the player can see Leon running around the map gunning down Ganados but can never be catched up with and will disappear before you manage to get to him, while you can hear gunshot and sounds of an ongoing fight with the Ganados (which is scripted). While in the castle chapter, Ada can find Leon in the castle fighting the Cultists on the other side, in the end of the game you can also see him fighting against Osmund Saddler; whether you catch up with him or mod the game to spawn him somewhere else or no clip through the wall, this AI of Leon will have no reaction to the player, nor get damaged once shot at and will most likely run around in circle loops due to being originally planned as a scripted event NPC.
Resident Evil 5
In the beginning of the first chapter in Resident Evil 5, Sheva and Chris encounter what appears to be normal civilians that stare at Sheva and Chris with suspicious looks, some of them are seen attacking a bag with what appears to be something moving inside. All of these Majinis cannot be interacted with nor killed due to not being armed at the beginning of this chapter, until meeting up with Reynard Fisher in the butcher shop. A cutscene will trigger before the butcher shop is reached.
Reynard himself serves as an Ambient AI too as he can only be interacted with once to let Chris and Sheva get in and hand over weapons and gear to them, leaving the butcher shop until he is killed later in a cut-scene, his corpse cannot be found as well.
In Chapter 1-2 of Resident Evil 5, it is possible to shoot Allyson and the Majini next to her when you first see them, but the bullets will not affect either of them due to the scripted nature of the event they are involved in.
Resident Evil: Revelations
The Partner Character AI in Resident Evil: Revelations in some episodes follow the player just like Sheva Alomar in Resident Evil 5 but is added there for story purpose as they cannot be interacted with, nor commanded, and they barely inflict damage on enemies, while in some parts you have to explore the Queen Zenobia alone by yourself.
- Koichi Hamamura, ed (2006) (in Japanese). biohazard4 kaitaishinsho revised edition. Enterbrain, inc. ISBN 4-7577-2638-4.
- ↑ Excerpt from biohazard 4 kaitaishinsho - revised edition, page 369:
"村への小道のトラバサミにかかった犬をアクションボタンで助けると、 のちに採石場でのエルヒガンテ戦で手助けしてくれる。じつは、 この犬は身体やワナに攻撃を当てることでもワナから解放できるが、 そんな荒っぽい方法では恩を感じないようで、 手助けには現れてくれない。"
- ↑ Excerpt from biohazard 4 kaitaishinsho - revised edition, page 367: