Urban games - activities that use the city as a game board - are pretty big over in the states. Pioneered by wacky college students with things like Pacmanhattan they now have their own festival - Come Out and Play.
Over here in the UK things haven't caught on quite as much, but it looks like it's starting to happen. Shoot Experience run photographic treasure hunts around London - the picture is a winning entry - and they've got an event on in the City on 30th September. Teams armed only with a digital camera look to solve clues and capture the answers in a defined area. Looks like fun.
Urban Golf has also developed a following - the Shoreditch Open is a full 18 holes amongst the asymmetrical haircuts of East London.
Dealing with cities often seems to involve the reclamation of urban spaces - skateboarding famously has found a home under the Royal Festival Hall - perhaps as a way of normalising an environment that our brains weren't really wired to deal with.
I think anything that encourages people to play more is a good thing and advertisers have the resources to engineer fantastic branded games - yet another way to deliver value. Don't just badge a venue - create something!