Games Workshop have released an app for their core fantasy game, Age of Sigmar.
The app is currently in Open Beta and is free to download. Once the Beta is over it will be available as part of Games Workshop's gaming resource service, Warhammer+.
The idea is that you can have all the rules and other information required to play the game stored onto your phone. The app comes with full rules resources and the army lists from the previous edition of the game, as the game's latest edition is pretty new. The lists from the new books (called Battle Tomes) can be unlocked by picking up the new books and inputting a special code in each book.
Apps that let you manage wargame rules are very, very useful. Not only does it save you carry lots of books everywhere, it also means you can create new strategies and ideas for the game in any place you'd normally bring a phone.