SCP began as a collaborative online horror fiction project about a fictional organisation that secures and contains anomalous objects and creatures, and its heavy doors, alarms and containment cells became familiar through fan games, videos and roleplay. The door close is now used online as shorthand for sealing something dangerous away, and it sits naturally alongside other horror game sound effects in tense edits, reaction clips and SCP fan content, where a single slam can signal that safety has returned or that escape is no longer possible.