Imagine a world that’s filled with invisible graffiti.

Is the world ready for virtual graffiti?

Imagine a world that’s filled with invisible graffiti. Open an app, point your phone at a wall, and blank brick or cement becomes a canvas. Create art with digital spraypaint and stencils, and an augmented reality system will permanently store its location and placement, creating the illusion of real street art. If friends or social media followers have the app, they can find your painting on a map and come see it.  Mark AR is one of the first projects built on Google persistent cloud anchors. The app, created by mobile publisher iDreamSky and Subway Surfers developer Sybo, debuted at last week’s New York Comic-Con, where visitors could borrow a phone and walk through a Mark AR pop-up installation, either viewing professional artwork or creating their own. Talented artists might use a virtual spraycan to paint freehand. Everyone else (including me) could pick from a set of comics-themed stencils. In the future, users could make their own stencils or even design images in Photoshop and import them directly.

Is the world ready for virtual graffiti?

Mark AR’s creators are planning more pop-up exhibits, and after these small trial runs, they plan to test the app in a single city. “A city launch will be where we’re testing: can we handle the moderation? Can we make sure people are playing safe?” says iDreamSky president Jeff Lyndon. “Once we can handle a city, we know exactly how we can scale our business to a national launch.” But if existing social networks have taught us anything, it’s that these are massive, complicated — sometimes even impossible — questions to answer. Mark AR’s creators are taking some cues from Pokémon Go — they’re going to geofence physical spaces like memorials to be off-limits, for instance. And they hope a real-name policy and the friend-based model will limit people making offensive or harassing images. “Because there’s no anonymity, that helps govern what people are doing,” says Sybo CEO Mathias Gredal Norvig.

But Mark AR’s whole purpose is imitating a public art form. So its most interesting uses involve, well, people making public art. It’s a natural fit for events like comic-cons and music festivals, where visitors come together in a physical space for creative purposes. And the idea of wandering around a city, finding the random tags people have left behind, is fascinating.