One of my pet peeves is a media (usually games) that expects you to read some source material for plot. Here I'm not talking about say you got Lord of the Rings where they try to stick true to the story but can't possibly fit everything there in the time so some events don't make a whole lot of sense and you got to check the source to find out what they can't cram in on limited screen time. Here I'm talking about say Xenosaga 1 or Final Fantasy XIII where you got this in game Wikipedia that tells you what some of the terms and abbervations that you can't possibly figure out what they mean in the game's context means. It's almost like an extra DLC for plot. Outside of movies, most non novel form of entertainment is at least long enough to get the basics of whatever you're trying to convey across. It's one thing if you're told there are 5 legendary whatevers and you only met one of them, and then later you decide to sell stuff on the other 4 legendary whatevers because they turned out to be popular. That's fine. But you shouldn't expect to know about a character that was never mentioned anywhere and what impact they had on the world.
I don't even understand why you'd do this, because while it's comparable to DLC, I'm pretty sure it's relatively rare you actually sell any DLC just because you left out a whole mess of plot details that's explained in the next DLC, and it's not like you need to go through all this loop to make DLC/spinoffs in any genre. Final Fantasy VII is a pretty self contained story and that didn't stop from all the spinoffs that come out when it turned out to be a huge commercial success. In fact, that contrasts very well with Final Fantasy XIII which seems to be considerably less successful than FFVII but just assumes all the 'please buy the next game to understand this big mystery' is somehow supposed to work. Heck, even Final Fantasy X-2 has more respect than that, as it's just a shameless magical girl spinoff but there was nothing in Final Fantasy X that ever suggested the goal of FFX was to transition into a magical girl spinoff.
I don't even understand why you'd do this, because while it's comparable to DLC, I'm pretty sure it's relatively rare you actually sell any DLC just because you left out a whole mess of plot details that's explained in the next DLC, and it's not like you need to go through all this loop to make DLC/spinoffs in any genre. Final Fantasy VII is a pretty self contained story and that didn't stop from all the spinoffs that come out when it turned out to be a huge commercial success. In fact, that contrasts very well with Final Fantasy XIII which seems to be considerably less successful than FFVII but just assumes all the 'please buy the next game to understand this big mystery' is somehow supposed to work. Heck, even Final Fantasy X-2 has more respect than that, as it's just a shameless magical girl spinoff but there was nothing in Final Fantasy X that ever suggested the goal of FFX was to transition into a magical girl spinoff.