Throughout the 2016 Olympic Games, the Canadian Tire Red Door to Rio gave Canadians the opportunity to engage with athletes, while the Olympians had the chance to connect with their fans and loved ones back home.

But in a surprise and delight twist, none of the participants knew whom to expect on the other side of the door upon stepping up to the experience, which involved real wooden doors, each bearing a large maple leaf and “We all play for Canada” messaging. Upon opening the door, participants were met with a massive, door-sized screen, along with a camera, microphone—and a mystery athlete or fan.

While the concept was simple in theory, pulling off the tech-fueled activation was anything but. How it worked: A low latency live-stream between Rio and Canada was developed with a custom algorithm to ensure smooth and natural conversations on both ends. A tablet-based registration system synched the doors to the stream, allowing technicians to record each side of the session then stitch the videos together. Partakers later received an email with a link to a video of their conversation for sharing across social media, where they were encouraged to use Canadian Tire’s Olympic campaign hashtag #StepUpStandTall.