The tenets of South Korean horror are usually good in using a setting or object to create a mythology. "Ghost Train" uses that in a similar way. What does work well is the build of this one to almost tell a Twilight Zone nature of a couple different people who have been affected by the train. It is not so much about the train itself but the station it inhabits which has its own past.

The perspective of "The 8th Night" uses the element of the "seeing eye" as an ancient curse but one where two sides of the same coin were separated by thousands of miles and millennia to prevent them from coming together again.

The texture of Korean horror is pushing elements beyond their breaking point in being both uncomfortable but mythic and cautionary in a certain way. "Metamorphosis" is a play on that idiom but it leans a lot on the basis of "The Exorcist".

Granted this inlay within "Warning: Do Not Play" has a bit of "The Ring" to it. Instead of a TV screen it is an old movie theater where a film was once shot and by extension a play. And there is a film that doesn't want to be found that was pulled from a film festival that the protagonist is searching for.