Circadian cycle	Day and night cycles on their own outside of plot, location, or triggered events, possibly influencing NPC activities accordingly.	1979 / 2019	451 games
Cloaked NPCs	Includes creatures that are either completely or partially invisible.	1993 / 2017	107 games
Dark	The environs are unusually dark, either because it's a perpetual night, you're stuck in a structure with limited light sources or anything else, forcing you to use any light source(s) you can find or cope with what little you can find in the env	1976 / 2018	387 games
Detector	Player must or can use special detectors that reveal things otherwise imperceptible.	2001 / 2015	27 games
Distorted vision	Something can cause the protagonist's vision to get distorted or otherwise impaired. Especially cases where the vision is always distorted	1994 / 2018	216 games
Facing	The direction people, vehicles, or any other things are facing affects gameplay in some manner.	1992 / 2018	89 games
Field of vision	Simulates field of vision to a degree, making characters unable to see 360 degrees unless they're nonhuman, augmented or otherwise different.	1998 / 2017	28 games
Flares	Hand tossed flares.	1999 / 2015	28 games
Fog of War	Employs a fog of war, especially when it restores it once no-one sees in the revealed area anymore.	1982 / 2017	212 games
Glow sticks		2007 / 2018	8 games
Vision indicator	Player is given some form of indicator of where other characters can see.		1 game
Infravision		1995 / 2018	11 games
Invisible foes	Includes opponents that are visually completely undetectable.	1992 / 2014	12 games
Invisible platforms	Platforms that normally are normally undetectable. Some may become visible under certain circumstances and others may even be intangible unless something is done to or near them.	1998 / 2018	24 games
Invisible walls	Players' ability to fully explore and/or utilize their surroundings is thwarted by unexplainable invisible barriers.	1990 / 2018	139 games
Portable light source	Player can employ a lamp, flashlight, torch, or any other device, magic, or natural phenomena that produces light to better see in darkness.	1981 / 2019	515 games
Light	Light and illumination plays a vital role in gameplay, and not simply by dispelling darkness.	1981 / 2015	29 games
Line-of-sight	Simulates line-of-sight to a degree, with objects blocking or limiting sight beyond them.	1982 / 2017	155 games
Nightvision		1997 / 2016	42 games
Radar	Player has a radar or similar device, or an unexplained display that mimics it, that gives positional info to player of various objects of interest and possibly friend-or-foe detection. Whether or not it is a literal radar.	1980 / 2018	378 games
Secrets: Invisible	Includes secrets that are completely undetectable until discovered, usually by bumping into them accidentally and revealing them.	1985 / 2014	18 games
Tunnel vision	A condition where person sees only the center (focal) part clearly or sees only that part with everything else indistinguishable.	1999 / 2014	9 games
Visible LASERs	Non-weapon grade LASERs are peculiarly visible to normal human sight.	1983 / 2015	78 games
Vision enhancer	Player has some device, ability or piece of magic that somehow enhances their normal vision.	1999 / 2012	28 games
Vision modes	Includes different view modes that convey different or additional information not otherwise available.	1995 / 2015	31 games
Weather effects	Weather plays a role that affects gameplay besides creating mood or limiting visibility.	1998 / 2018	60 games
Weirdvision	Any vision mode, tool, or such that can't be adequately described by anything else. Often has a name that suggests scifi tech (e.g. nanovision), supernatural powers (second sight), or such.	1999 / 2017	49 games
X-ray vision	Any vision mode, tool, or such that allows the player character to see through walls and other vision obscuring obstacles, regardless if it's literally an x-ray vision or not.	2000 / 2016	24 games