Keeps you occupied—but cant sign into Game Center

I like these types of games that dont require much thinking and help pass the time, if you have time to pass.

But theres a bug, I believe, with Game Center. The first time I ran the application, it asked me to sign into Game Center, which I didnt do at the time. Now I would like to sign into Game Center, but there doesnt seem to be an option to do it after dismissing the option to do so the first time. Ive checked under options and everywhere else in the application and dont see an option to do this.

MarcusAurelius24 about Line Runner 2