How it’s done
It's the oldest game in the world and the easiest to underestimate. It starts by covering your face with your hands and reappearing, and ends, years later, with the child hidden behind the curtain holding back a laugh.
What never changes is the emotional mechanics: the small tension of the absence and the happy relief of the reunion. So don't skimp on the acting: the faked surprise ("wheeere were you?!") is half the gift.
It needs nothing more than your presence and your face full of wonder.
What it builds — the why
In the baby, nothing less than object permanence: understanding that what disappears still exists — the foundation of the security that Mom and Dad come back even when they leave. Later on, self-control (staying still and quiet), strategy, and the pure joy of a shared game. The thrill of the reunion is what seals the trust.
How it changes with age
0–2 Babies
3–5 Early childhood
6–9 Childhood
Variations
Tired-baby version: just covering and uncovering your face, without moving, works the same. Family version: sardines — one person hides and everyone searches until they end up crammed into the same hiding spot, dying of laughter.
What to watch for in your child
Some children are thrilled by the tension of not being found; others, very young, are distressed by it. If your child gets scared when you disappear, shorten the absence and play up the reappearance — the game should always end in relief, never in a real scare. His tolerance for the wait tells you a lot about where he is today.