A large and interactive gaming experience right in the middle of a city will definitely draw attention from passersby, which is exactly what the City Fireflies game is doing in Madrid. This large urban game was designed to "explore new ways of interaction in public spaces," says the creators, Victor Diaz and Sergio Galán. Located at the medialab-prado facade in Madrid, the City Fireflies game only requires players to have smartphones.

The goal of the game is to rid the square of little evil-looking 8-bit characters; to do so, you have to physically move around and "sweep" the characters off the large video screen, says Fast Company. It's a multiplayer game, so the more people who play together, the better the chances of clearing the square of "threats." And, rather than having players download an app to play, the City Fireflies game works by simply tracking the glow of the screen on a player's smartphone.