Playing in the city

I am currently at the Making the City Playable conference in Bristol, and thinking about playing in the city.

Some of the ways I play in the city:

Location based games, using a phone, such as Ingress.
Recently, also, Zombies, Run! (Well.. Zombies 5k - Couch to 5k equivalent).

I think also that ways of exploring / experimental travel techniques are also a form of playing in the city:
Using phone apps, such as Serendipitor, Dérive app, and cards such as Drifft.
Flâneurs Dreamwidth Community June challenges.
Latourex.

Also, I play games such as:
SFZero.

I also enjoy the ways in which people have made the world seem more playful, from art installations to rope swings to a postbox that has eyes.

How about you? How do you play in the city, or play with the city? What playful interactions do you have in the city or with the city?