Every motion game I've ever set up starts the same way. Stand here. Put your arms out. Hold still. Now do it again, because the kid wandered off. By the time the calibration bar fills, the six-year-old has lost interest and the dad is holding a T-pose alone in his living room.
Sky Peck has no calibration screen. It never will. One set of numbers has to work for me and for my son, and he is about half my height. That rule sounded like a constraint. It turned out to be the whole design.
Everything is measured in you. The camera never asks how tall you are or how far away you're standing. Wingspan is your wrist-to-wrist distance divided by your shoulder width. Flap height is how far your wrists rise above your shoulders, measured in torso lengths. Lean is the tilt of the line from your hips to your shoulders. Step closer, step back, swap the dad for the kid, and every ratio stays the same, because the ruler is your own body.
It learns the small things and refuses to learn the big ones. Nobody stands perfectly straight. The game slowly learns your resting lean, over about ten seconds, and cancels it out. But it only ever cancels a small tilt. A real turn is never absorbed as "the new normal", because that is exactly how a kid ends up leaning harder and harder just to fly straight. On the VR headset, where there's no camera at all, the wingspan learns itself from the widest stretch you show. Stretch once and it knows.
The camera is slower than the game. A webcam hands over a new skeleton twenty to thirty times a second. The game draws sixty or more. Read the lean straight off the camera and the parrot turns in little steps, a staircase you feel as jerkiness. So each step gets spread across the next few frames, and the turn comes out as one smooth bank. It sounds tiny. It's the difference between a bird and a robot.
Telling a dash from a flap. The propeller dash is arm circles: crank both forearms and the parrot rockets forward. Flapping is also arms going up and down. The trick is direction. A spin turns the same way the whole way round, while a flap goes up, then down, and averages out to nothing. Watch the direction, not the speed, and the two gestures can't be confused. The first version got it wrong in a funnier way: cranking your arms brings your hands closer together, and hands together means dive. So the parrot dived the moment you asked it to dash.
None of this is visible, and that's the point. The kid walks into frame and the bird just flies. And when it's dad's turn, he doesn't have to hold a pose either.
All of it happens on your device, by the way. The camera reads a skeleton, throws the picture away, and the skeleton never leaves the room.