It's the designer's go-to guy. If they want to steer a player in a given direction they'll lock an in game door and force the player to find a way to either unlock it or find an alternate route.
The player character is seen at a distance from a number of different possible perspective angles. There is generally a movable camera but it can also be in a fixed position. It most commonly refers to a viewpoint behind the player character.
A gameplay mechanic where the player must make narrative decisions or dialogue choices in real-time, within a certain time limit, with their choice (or lack thereof) affecting the plot.
A spell or special ability which is used to either repel the undead or outright destroy them.
In order to circumvent various obstacles, some protagonists must travel through ventilation systems.
A sub-genre of adventure games, visual novels are interactive fiction that usually have very little in terms of gameplay but focus more on extensive storytelling, character interactions, dialogue trees, decision-making, and branching narratives, as well as artwork, cutscenes, voice acting, and music.
Games with organic tissue covering or growing out of the walls (or floor). Typically seen in horror games. This concept does not cover situations where characters are actually inside larger organic beings.