Top Down Stealth Toolkit Basics: Stimulus Types

The v2.0 update for Top Down Stealth Toolkit introduces a new Stimulus generation system that will enable the users to easily customize & add new types of perceivable events for the AI agents. Inspired by the AI Threat Detection system used in the 2D Stealth game - Mark of the Ninja, the stimuli are primarily divided into two categories: Targets & Interests.

The Target Stimuli represent the highest level of threats that can be perceived by the enemy AI. Once an agent has acquired a target, it will focus all it's attention on the said stimulus, with complete disregard for anything else until the target actor manages to evade it's line of sight. The Player Character is an example of an entity that registers itself as a target stimulus.

The Interest Stimuli on the other hand, represent cases that require some level of preemptive investigation before an agent can make further decisions. These are more varied due to the multitude of attributes that define them (more on this to be added in a later post), & hence split into the following categories:

  1. Incapacitated Ally: AI agents that get incapacitated at any point of time will register itself as an Incapacitated Ally. These interests will continue to exist for as long as the agent remains in the said state. However, since they support interaction by other agents, the stimulus creator can be brought back to an operational level, at which point the interest will be set to a deactivated state.
  2. Defunct Ally: Created when an agent gets terminated & will remain an active stimulus till the end of the level. These interests keep track of agents that have been alerted to it's presence & hence ensures that a single agent will respond to it only once.
  3. Alarm Noise: Created whenever an alarm has been raised by any entity. Has a very short lifespan, but can put agents on a high alert state.
  4. Gunshot Noise: Created when a non-silenced weapon is fired. Works similar to the Alarm Noise interests at a functional level.
  5. Missing Suspect: Created by AI bots based on the their memory about the last seen location of a target. Can only be perceived by the agent that registered the stimulus, but requires no form of range checks.
  6. Footstep Noise: Noises created by the player character's footsteps can be perceived by AI agents through these type of interests. Has a very short lifespan, & generally perceived as a medium level threat.
  7. Whistle Noise: Functions similar to the Footstep Noise interests, but created when an entity uses the Whistle.
  8. Peripheral Motion: Represents all entities that can be perceived by AI agents based on the proximity level. Unlike other interests, this stimulus will remain active throughout the lifespan of the actor responsible for creating it. However, owing to the indirect nature of perception used to detect this form of stimulus, the AI bots will react only if the stimulus creator remains in close proximity for a certain period of time.