Mostly going over thoughts already stated in forum and consolidating them. Where magic is used as a term here, it is a general catchall for anything that is not considered presently understood or which is easier to handwave off as “an alien wizard did this” rather than any specific system of thought or mechanism.
Sight
Description: The ability to visually recognize through interactions of objects with the light, this is limited by light and visual acuity of the character in question. Processed by retinal nerves in common Earth creatures.
Expansions:
[ul][li]Stealth: In combination and consideration with various conditions, may be blocked. For example, actors toward someone adjacent to the wall in “low light” weather to represent moving under shadows.[/li]
[li]Invisibility: True invisibility, magical or technological. For example, active camouflage or actors which are aliens not in sync with our plane.[/li]
[li]Facing: Where facing is meaningful as a concept, vision projects from a cone from facing direction. Vehicles with 360 degree cameras or creatures with multiple eyespots may see more than such.[/li]
[li]Poor vision: Actors with extremely poor vision such as spiders; in reality they track motion. Perhaps easier to represent here with sound sensitivity and low vision. [/li][/ul]
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Sound
Description: Perception of vibrations in the air or water intepreted through auditory channels in common earth creatures.
Expansions:
[ul][li]Echolocation: Perfect awareness of the exact presence of objects in a radius as the sensing actor emits noises. [/li][/ul]
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Scent
Description: Perception of olfactory or chemical clues through nasal glands.
Expansions:
[ul][li]Pheromones: Certain scents may provide rich information to actors beyond simply presence. For example, how ants communicate. [/li][/ul]
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Spatial Awareness
Description: Catchall for any other forms of knowing presence in an area. Sometimes akin to "cheating."
Expansions:
[ul][li]Knowledge: “Cheating.” Actor is provided template information of the building, assumed from previous understanding.[/li]
[li]Technological: Radar, infrared, etc. Blocked by special criteria depending on how it functions. [/li]
[li]Sixth scene: Actors “just” know presence of targets. Couples into other forms of magical understanding. [/li]
[li]Magical: Alien telepathy, etc. Blocked by the special function or criteria depending on its methodology. [/li][/ul]
In addition, communication should be considered. For example, consider the below:
[ul][li]Scenario A: Invisible or stealth antagonist observes the player character and communicates this information to a companion. Therefore, companion takes action against the player.[/li]
[li]Scenario B: An antagonist uses magical awareness to spot and take action against the player.[/li][/ul]
In both cases, the player finds himself at the target of hostile action without warning, however, the actual cause and therefore interaction steps with both are quite different. The former allows the player more interaction opportunities(hide from the scout, kill the scout, etc) while the latter requires the player to block the exact form of magical awareness being utilized - essentially more unfair and probably a less encouraging design.