The term "spin-off" arrives with an implicit negative connotation, effectively suggesting it's a knock-off of the original. But is being a second such a terrible thing? Sure, they might be more hastily produced than the real McCoy, but they're generally cheaper, and only occasionally fall apart at the seams.
Video games have seen their fair share of shoddy side-games, with the particularly terrible ones making the word mud (Link's Crossbow Training, anyone?). But not every one has been a steaming pile of Tottenham, an utter load of Hotspur. In fact, some have even been so good they've eclipsed the series they flung away from.