Lucky Kat World (mobile) app is designed to take advantage of the latest features available to iPhones and iPads. All of the LKW mobile apps for IOS work on IOS 7.0 and above.
If you have an iPhone or iPad with IOS 7.0 or IOS 7.1 you may see some things in the app slightly misaligned. On smaller devices like the iPhone 4, some of the top and bottom of the app is hidden due to the size of the window on that device. All buttons and interactive elements are inside the viewable area.
Upgrading to IOS 8 is easy. The best way to upgrade your iPhone or iPad is to connect it to your computer and start iTunes. This requires less space on your device and doesn't tie up the device while the upgrade is downloading.
Below are a few links to instructions on how to upgrade using iTunes.