The Blackout Club is a multiplayer horror game about teenagers sneaking around at night trying to avoid sleepwalking adult cultists in their hometown of Redacre. If you opt-in to its "Enhanced Horror" setting The Blackout Club will have access to your microphone, listening in so that the developers can mess with you personally.
Spoilers follow, as these interactions are revealing both the game's lore and unfolding a plot as it happens. Most recently they've involved a being called DANCE-FOR-US (DFU for short) who is an ally of the players, encouraging them to dance and not be afraid. Also, she may have taken some of them to the moon briefly? The Blackout Club's disembodied Voices can teleport players around so they're not being chased or running around on rooftops while interacting.
These interactions are portrayed by actual voice actors, live. As you can see in the video uploaded by @LeighaSolo above, an actor chats to the players in-character, even referring to them by name, getting to know them a little before the event kicks off and suddenly things stop being chatty and start getting dark.
Players have been recording similar interactions in the months since The Blackout Club was released (and even before that during the beta), like this conversation with DIE-FOR-YOU below. It's a fascinating way to tell a story, and there's not much else like it in videogames.