Like a lot of TTRPG words, it gets used in different ways. I think of it as a project (especially from the 90’s and 00’s) that someone would sink a ton of energy into. Usually they were/are fantasy games to “replace DnD”. They’re heartbreakers because online sales weren’t really a thing back then, so a person would pour their soul into making the next big thing and spend lots of money on publishing it.
In this context, I’m saying that this is a passion project. It’s kind of for an audience of one. So, I’m currently working on slightly more achievable smaller projects but I hope to come back to this big one eventually.