LONDON—At the ripe old age of 28, Patrik Sättermon considers himself over the hill as a professional videogame player.

"For some games you have to be super fast, and at 24 or 25 you're past it, you're a veteran," says Mr. Sättermon, a former world champion in the game Counter Strike. "You don't realize your reflexes start to disappear, but you see it on the scoreboard."

So Mr. Sättermon—a Swede who is the Chief Gaming Officer at Fnatic, one of the world's top pro gaming teams—is out to groom the next generation of screen jocks.

At the Fnatic Academy he runs in London, he accepts just six teens a year. Eventually, he hopes they will become not just professional players, but stars.

"The peak age for a gamer will be 18 or 19," says Mr. Sättermon. "That's when you have the right balance between reflexes, the ability to understand the game and also enough maturity."