- There are some showstoppers that apply to all products: Reliability, security, trust, ease of use, speed, customer support.
- To find gamechangers you need to think outside the box. Most people accept things as they are. Most people run away from schlep work. The only way to find gamechangers is to question everything and add a question mark when you find yourself saying "that's not possible".
Remember that a showstopper is defined as "Something that will prevent a customer from buying your project." Sure, reliability, security, trust, ease of use, speed, and customer support are always nice to have. But part of building a startup on limited resources is knowing what's nice to have and what will prevent a customer from buying, and not spending resources on the former. You can always go back and fix the nice-to-haves later when you have more resources; you can't go back and resuscitate a company that runs out of money.
So for any combination of product attributes, you appeal to some market of size n, and are unappealing to some other market of size z. The question is how do you build a product for which n is sufficiently large, acknowledging that you can't satisfy everybody at the same time.
Expanding beyond just product attributes, this whole discussion aligns with the thinking from The Discipline of Market Leaders which talks about how you can choose to construct your value proposition based on optimizing one of three possible axes (where product excellence is one), while striving for merely "acceptable" on the other two.
Since different markets will purchase based on different value propositions, the important thing (or so the authors argue) is just that you be really good at one of the three, and just good enough at the others.