tbh the idea I have is extremely niche and it's more of a "I've played too many of these games and they get a lot of things wrong" situation where I'm the only one who cares.
Even if you only find a small audience you're in a better position than most trying to do what Team Cherry did. They pulled from many sources of inspiration from the Metroidvania subgenre (and related subgenres) and nearly perfected it. That is much harder than discovering and filling an open niche
Also cosigning @dwoboyle.com's recommendation to start with small modules (e.g. small-scope minigames or micro-projects that you can crank out in a week) and build up from there
