This is more of an auxiliary addition than a game, although the game component is also present, but without GTA 5 makes no sense. The app's two main tasks are training Chop and modifying vehicles, but there are a number of other functions as well. Synchronization with Rockstar Games Social Club provides instant progress updates in GTA 5.
Chop is trained by completing three fun mini-games where you need to earn as many points as possible. In addition, you can change the collars (but first you need to open them), and you need to feed and water, walk and clean up after the dog - a natural Tamagotchi.
Modifying transport is a completely different process. Here you are simply tuning your vehicle fleet. However, it is important to know what you are dealing with, as the images here are schematic.
An excellent free application that complements GTA 5 well. Another small plus for the series.