The next battle in the ongoing Planet of the Apes fracas is 20 months away, but today we get a little snippet of behind-the-scenes footage — and a challenge from the Simian in Chief. Andy Sirkis and director Matt Reeves have taken to YouTube with a challenge: Walk like an ape and be in their movie. Fans can submit a video of their “most lifelike ape imitation,” and one knuckle-dragging winner will be flown to the set to participate in “Caesar’s greatest battle yet.”

There’s still time to practice your chest thumps and guttural grunts: Fox’s War for the Planet of the Apes begins its campaign July 14, 2017.