“Uncut Gems” actress and filmmaker Hailey Gates had her plans for a documentary about military training villages upended by government officials. So she turned the idea into an unconventional love story instead, and “Atropia” was born.

The film, which premiered on Saturday at the Sundance Film Festival, was originally conceived as a documentary about fake Iraqi villages built on U.S. military bases post-9/11.

“I initially wanted to make a documentary about these fake villages that were built on bases in the U.S. after 9/11 to train soldiers before they deployed to Iraq and Afghanistan,” Gates told senior writer Drew Taylor at TheWrap’s Sundance Studio presented by World of Hyatt. “The military was not so keen on the version of the doc that I wanted to make, so we decided to be satire.”

“Atropia” follows an aspiring actress at a military role-playing facility who falls for a soldier cast as an insurgent,...