Almost every game nowadays is born with a theme and story embedded in it. It is logical, since there is a specific market that appreciates the storyline of the game even better that the gameplay itself. Nothing is wrong with that. Theme/story approach in game designing is probably one of the biggest entrance actually to design a good game. This has made many game designer have become more than “just” a gameplay engineer. They also transformed into better and better story teller nowadays.
One of the most important thing in storytelling is the universe creation itself. You need to understand how things are made in your world, how matters collide, how people interact, how many species and so on. Those boundaries is the universe itself. Only after you have fully create the universe than you can let your player understand the storyline as well.
Thus creating the genesis book of your Intelectual Property is indeed a must thing to do.
But in industrial point of view creating a mere perfect universe if now far from enough. We probably remember when in 1993 DR Richard Garfield proposed his game for the first time to publisher. It was the universe he was presenting, the races, the main characters, the power, and at the end the interaction boundary that is the gameplay itself. He was talking about Magic: The Gathering, one of the best trading card game in term of story and revenue up until today.
Many universes came after MTG and barely survived. Creating a perfect universe was no longer sufficient to sustain.
Until in around 1999 Pokemon TCG was released. Pokemon, started its first step in Gameboy, launch its trading card game but not without different approach. After the universe creation has been completed, they tried to approach the market differently, they put animated series in Sunday morning television channels, and after that they sold the card game on conventional mass distribution channel rather than hobbies store like any other TCG. The approach was a success! Thus it was then copied by many such as Yu-Gi Oh and Vanguard, one of many that still survive nowaday.
Storytelling is indeed one of the most important aspect in your game, but at the end you want to make sure that your game sustained. Collaborate with many people, such as novel writer, comic author, or even animation studio will help you boost your universe or IP’s fame even better. After that, you need to make sure your product is sellable. Understand your player even deeper, understand when and where will they spend their money to your game, and create even better strategy to meet them in the market. Those are how you maintain your universe and make it even bigger.