Exercise games for kids, free, on a webcam

The problem with exercise for kids is the word. Say "workout" to a six-year-old and you get a negotiation; put a game on the screen that only moves when they move and they will do twenty squats without noticing they did any. That is the whole trick here. The Hopla Ninja Academy is 35 free movement games where the webcam is the controller: the browser tracks the kid's arms, legs and head on your own device, and every game turns one physical skill into something worth scoring.

The moves are the ones a PE lesson is built from. Jumping over bars, squatting down small and stretching up tall, marching on the spot with the knees high, standing on one foot for balance, dodging under things, flapping the arms, punching targets as fast as you can. A round is one minute — short enough that a four-year-old finishes it on Rookie, sweaty enough that a thirteen-year-old feels it on Master — and the kid who stops moving stops scoring, which is the part a fitness video can never enforce.

Nothing to buy and nothing to set up. A laptop, a tablet on a shelf or a computer plugged into the TV, a webcam and about two metres of clear floor is the entire kit; it runs in Chrome, Edge and Safari with no download and no account. The camera image is processed inside the browser and is never uploaded, stored or recorded — there is no server that could receive it.

Every game has four ranks: Rookie is very forgiving for a preschooler, Master is a real workout for a teenager, and a round at a higher rank earns a better medal. Points are never taken away, and two kids can play side by side sharing one score, each on their own rank, so a six-year-old and a twelve-year-old can burn energy together without it turning into a fight. Free, all of it — a rainy-afternoon PE lesson at home that the kids ask for.