something i dont think people really get is that when development of a game is say, 80% finished you don't have 80% of a game, you have 0% of a game and 80% of the disparate parts that would make up a game if they were actually 100% done and put together
so i need to elaborate on this since it seems to be confusing some people. when i say 0% of a game, what i mean is experientially, as games are experienced by people who play them, you have 0% of a game. before a game is finished you don't have a game at all. it's like having the parts of an ikea flat pack sprawled across your living room floor. like, you have 100% of the parts that make up a shelf, but i don't think, experientially, you can call the mess of disparate parts a shelf
i know there are exceptions. some games, as they're developed, remain more or less playable throughout the development process. but this is the exception and not the rule, because it's hard, time consuming, and kind of inefficient. this is why you mostly see big companies with lots of money banked doing this. they have that luxury (and it is a luxury)
if you're not doing that then, yeah. you have mechanics. and you have levels. and you have side activities. and you have world maps. and you have minigames. and you can, with some effort, fire up an executable for the game that lets you access some of these. but that's still not a game. you're not experiencing most of everything that makes up the game at the same time, in its proper context. you can set up a way to do this, and then you have more than 0% of a game, but doing that is a task in and of itself which is often left for very near the end of the project
so the subjective experience of developing games is that you're treading water working on a whole bunch of parts for a very, very long time. and then suddenly, one day it all comes together and then you have a game. and then you're probably going to ship not long after that
EDIT: put another way, if i say 90% of Kitsune Tails is done, that doesn't mean that i can send you a build that you can fire up and experience that 90%. in general, the percentage that you'll be able to (seamlessly) access is going to be orders of magnitude lower
I have 100% of the thread I need for a cross stitch pattern. I have some percentage of the thread stitched into the aida. But I still have 0% of a cross stitch project, because I can't display what I've done so far and have people be like, yes, this is x% of a pattern. Folks who see it would be like, this is not a pattern, what the hell am I even looking at? I couldn't try to donate it as a prize for something, cause what organization would advertise x% of a cross stitch as a prize you could win for donating?
Like, realistically, yes, I've done x% of the work, but that doesn't count towards the finished product because it's not finished. I can't do anything with it until I've done 100% of the work. This is essentially my understanding of what the OP is saying, but in different wording.