It has a city hall and a city council. A vintage art deco theater, a harbor and a fair amount of traffic. And plenty of billboards, of course. But despite brownstones, diners, skyscrapers and bridges, this city is no recognizable metropolis — plus, it’s all bathed in a luminous purple glow.

Welcome to Roku City, the violet-hued screen saver for the widely used streaming platform that’s become a quirky, ever-changing diversion for over 100 million viewers, a canvas for imaginative ads and an increasingly important branding opportunity for the streaming platform.

Roku City has been scrolling across television screens since 2017, hiding Easter eggs by the dozen and hosting ad campaigns for companies including McDonald’s and Walmart and promotions for studio films, Emmy campaigns and talent like Demi Lovato. (Next year, Roku is set to become part of Fox Corp. under a $22 billion deal.)

The most chatter from fans of Roku City — yes, a screen saver has many, many devotees — springs from the Easter eggs, a revolving selection of more than 40 pop-culture moments and nostalgic references that populate the screen. Recently, viewers discovered Jimothy the raccoon scampering through the city. His appearance led to a sizable 12 million impressions on social media mentioning that the curiously shaped raccoon was paying a visit.