After what feels like a decade of waiting from being broke, I finally picked up a copy of Shin Megami Tensei: Devil Survivor: Overclocked, a spin-off of, well, the Shin Megami Tensei franchise. I haven't completed it yet, but I'm thoroughly enjoying my time with the title, I like it much more than the actual Shin Megami Tensei games and equally as much as its sister spin-off series, Persona.
Sometimes spin-offs just manage to outdo their parent franchises and they can appeal to a much larger audience than them as well. Mario Kart, Metroid Prime, Rune Factory, and even Metal Gear Rising: Revengeance are all highly notable spin-offs that many people love dearly despite their departure from the core franchise's gameplay mechanics, story, or even universe. They're loved by many and some have even been successful enough to become their own sub-franchise, sometimes even outdoing the main franchise.
So tell us, what is your favorite video game spin-off franchise and why do you like it so much? What do you like about said spin-off franchise the most and if applicable, does it outdo its parent franchise in any way?