Plot Armor is one of the fairly few terms very widely used recognized outside this website. Looking at the page and examples, it's also a very unclear term we're doing a poor job with.
The cause of this is that, as it is, Plot Armor is defined as quasi-amalgam of two different phenomena that are superficially similar enough to confuse.
Bob survives a certain death situation through contrived circumstances or 'luck.' This is the definition most content on TV Tropes seems to use.
Bob cannot die because of 'reasons.' Significance to the plot, importance to the franchise, favored fan character, the work is a prequel to something Bob appears in. This is the definition the Laconic Page uses. It's also the definition the name strongly implies.
Although parallels exist, these two definitions are not at all the same. Minor characters with little to no bearing on the plot can and have survived circumstances they should have died. (Meeting definition #1 and not #2.) And there are plenty characters 'necessary' to the plot throughout fiction who have never survived a certain death scenario through contrivance. (Meeting definition #2 and not #1.)
In particular, very close attention needs to be given to video game plot armor examples. Looking at the current examples, almost all of them need to be scrapped. We need to be clear on phenomena that arises from writing and phenomena that inevitably arises from the construction of a game (E.g. Not every character can be killed be the player.)