This scene in Juan Antonio Bayona‘s The Orphanage (’07) in which Belen Rueda summons the ghosts of several children by playing the game “Uno, Dos, Tres, Toca la Pared” (i.e., One, Two, Three, Knock on the Wall), is one of the most genuinely creepy and unnerving scenes in the annals of adult (i.e., subdued) horror cinema, and it was done without resorting to a single visual effect.
Somewhere between 98% and 99% of horror filmmakers wouldn’t be able to deliver a scene like this if their lives depended on it — the idea wouldn’t even occur to them — and that is what I despise about the horror genre.
I’m sorry that this clip is underlit, but you can make out what’s going on with the kids slowly making their way into the room. The sound of the creaky door suddenly being opened off-screen is brilliant.