Although it's obviously not Connect 4 because that's trademarked.
Perhaps Apple's bizarre decision to cut loads of holes into its new range of iPhone 5C cases wasn't so weird after all?
A new app called Flipcase uses Apple's accessory to turn an iPhone 5C (or indeed any iPhone you can cram into the case) into an ideal portable not-Connect 4 set.
It's best described in the video below. Users are required to flip the case back-to-front. You can play against the AI or pass the device between you and an opponent.
The app is free, incidentally: