It’s a lot of fun. I just found out about it last year and did the Calgary one. It’s very well organized and it is a great way to explore the cities. There is actually a picture of me in one of the 2006 Calgary City Chase pictures on the City Chase website. Guess which one :).
At one of the Chase Points, I had to get shot in the back with a paint ball gun by my partner. That hurt like hell! The only protection I had was my t-shirt!