Spin-offs provide a huge wealth of opportunities for developers, allowing them to explore further aspects of a series' universe that’s otherwise out of place within its original format.
A lot of these take existing support characters and move them into the role of the playable protagonist, developing their storyline further. Others will utilise the same setting but feature a completely new storyline and characters, often for the sake of convenience.
Sometimes developers simply wish to use their existing setting within a new genre, providing a completely different experience. Halo Wars is one example of this, moving the famous FPS franchise into the RTS genre.
This process has seen some shameless cash-ins too, leveraging a popular brand for extra money and resulting in some awful games, like Resident Evil’s Umbrella Corps, Metal Gear Survive and Animal Crossing: Amiibo Festival.
But this is far from the rule and a lot of spin-offs went above and beyond, ending up as recognisable as the main brand, if not more so. Even better, sometimes these even surpassed their parent series in terms of quality and popularity.