There are many different ways where the idea for a video game comes to the forefront within the Indie designer's mind. For some the germ of the thought begins with a generic environment. It could be outer space or an isolated island or even an urban environment. For others it can something completely made up and completely foreign to a logical mind. This is what is so great about being an Independent designer/developer, we get to start with a blank sheet of paper and fill it in with whatever our mind emits.
I was extremely fortunate for I had the chance to develop my own stories, my own sub-world and my own characters before I even began the blueprints for my game(s). Why in my view was this so important? If you as a designer can conceive and construct open-ended environment and tales where characters can evolve and continue, the subject matter for future gaming projects never dries up. The amount of fresh and vibrant material a designer/developer can present to his/her customers is not only satisfying but also profitable (hopefully).
The capability to tie one game to another adds continuity or I should say, a never ending reservoir for the expansion of the world you established. It is a world where you as the creature want others to enjoy, experience and interact. I should also say, as an Indie designer, it keeps me focused and relieves some of the pressure toward facing an unknown distant future where at times, ideas dry up.
The downside, of course, is the possibility of producing one game after another with too many similarities to intrigue new purchases from an ever growing discerning gaming public. But this is contrary to the who conception of being an Indie game designer/developer. Who said you have to follow a specific and normal route toward creation? The absurd and the un-wielding is our personal domain within this great industry.
For instance, I have tied in within one world a giant politically incorrect Chupacabra and an incompetent homicidal 26" Rodent. How and why? I just did. I know, in the future I will always have something to build upon. It brings me joy to see it all come together. After all, is than not part of being an Indie?