Anki, whose racing game powered by artificial intelligence has seen surprising success, is announcing the sequel today at the New York Toy Fair. Anki Overdrive, which will go on sale in September, adds brand-new cars, a modular track, and bridges that make races thrillingly three-dimensional.

Anki Drive — a racing game with Hot Wheels-style robot cars powered by your smartphone — was the No. 2-selling toy on Amazon this holiday season; the company sold out of its inventory 10 days before Christmas. It's a novel concept: you steer a car using your own smartphone, racing against the A.I. or friends who are racing using smartphones and cars of their own. But since the day the game launched in 2013, players have asked for a modular version that let them build their own tracks. It was easier said than done: designing a track that can be easily reassembled took the company more than two years.

The result is a track made of a flexible but sturdy material that snaps onto other pieces via inconspicuous magnets at the end of each piece. The Overdrive starter kit, which will retail for $149, contains enough pieces to create eight different tracks. Anki is selling expansion packs that let you add a four-way intersection, a U-turn, or a jump — and having watched a series of A.I.-powered cars soar flawlessly over a gap in the track, I can't imagine anyone who buys Overdrive not wanting one. (Expansion packs cost between $10 and $30; the starter kit comes with two cars, and each additional one costs $49.)

On the software side, Anki has invested heavily in enhancing the video-game aspects of each race. The anonymous A.I. opponents have been replaced by fictional commanders who come with strengths, weaknesses, preferred virtual weapons, and a back story. They’re the brainchild of Joby Otero, Anki’s chief creative officer, who previously was the creative director of another game blending physical toys and video games: Activision’s Skylanders franchise.

When it launched in 2013, after four and a half years of working mostly in secret, Anki’s founders said that its toy cars were only the beginning. Eventually, they said, they would build powerful, low-cost machines that went beyond entertainment to do real work. Last week I asked Hanns Tappeiner, an Anki co-founder, how that was coming along. For now, he says, the focus is on the game. "We’re spending some time on other things," he says, vaguely. But most of the company’s energy is going into the game.

After playing a round of Overdrive with Tappeiner, I suspect that kids — and anyone who has kids — will like it a lot. The modular track is designed so you can lay it on top of anything and the race will still work. Stuff a sweater under there, or a pillow, and suddenly your flat track is a series of hills. Overdrive is still relatively expensive for a toy, and some parents won’t be eager to replace it after just shelling out hundreds for the first version. (All your old cars will still work on the new track, though.)

But between Skylanders and Anki, hybrids of physical toys and video games have never been so popular. The robot butlers that I expect Anki to build for us eventually are still a long way away. In the meantime, Overdrive is a good-looking step forward.