UPDATE 2016/02/16: This simple project has also been open-sourced on GitHub!
During my parents' recent visit to San Francisco, my mother and I checked out the local Exploratorium science museum. I loved some of their interactive visual displays, and decided to build my own rendition of “Conway's Game of Life” for the iPhone/iPad that same night.
It's a pretty simple game, but has some nice effects and only took me a few hours to code. There's iPad support as mentioned, and it of course bears a stylishly flat “iOS 7” design and icon. Check it out! (it's free)