Oh, it's been a while...
There's a general agreement that the leading digit should always be 0 until you have a complete game that's playable from start to finish with all the features, plot points, and polish that make it "finished" and any update after that is gravy.
No, and I really mean no, there's not a single agreement when it come to versioning. At most the semantic versioning scheme (Major.minor.patch[alliteration]) is supposed to be the most used one, but no one is really sure.
But well, let's say that there a general agreement, because it's funny to demonstrate why it should be this one.
Side note: It would be also funny to demonstrate why the one I will come to shouldn't be it itself
- Major
Mark a significant change in the software. Can be either the addition of significant features, a paradigm change, or a refactoring that don't guaranty the backward compatibility.
The Major version number must be incremented each time there's no guaranty that a previous version would be able to fully understood and proceed the data generated by the software.
- minor
Small changes in the software. Any addition of features/functionalities that do not change the effective behavior of the software "data side".
The Minor version number should be incremented only when the change do not correspond to a bug fix or vulnerability patch, and do not prevent the previous version to fully understand and proceed the data generated by the software.
- patch
Any change in the actual code that fix instead of adding. In can include pure code refactoring when they are done to improve the performances.
- alliteration
Fuck, we forgot/messed something with our previous patch. Please, pretend that you seen nothing.
So now...
The consensus on the Open Source community, is that a software should only stay at a Major version 0 during its early process.
This number represent the alpha stage of the software. It's the period during which the stability of the software is not guaranty. Only experienced users should use it at this time, because there's risk to loose your data, damage them, and it can possibly generate some OS instabilities.
Once the stability the software is reached, there's no more risk for the data, and the main features are implemented, the software should pass to the Major version 1. This will tell to the public that it's now safe to use it, even when you are an inexperienced user.
Therefore, at least when it come to VN-like games on the scene, there's clearly no reason for any version, except an effective early demo, to ever be a 0.m.p. The main features are implemented, the game is as stable as any other, and there's no risk to use it, the first release should be numbered 1.0.0.
This being said, there's another issue here, once again, "at least when it come to VN-like games on the scene". Why the fuck should the following releases be numbered at minor level ?
At no time those releases represent a small change in the game. They all implement significant addition, and strictly speaking the previous version wouldn't be able to understand and proceed the data generated by this new version.
Therefore, every following release should have a change in the Major version. This unless they correct a bug (patch) or add a new feature to the game but absolutely no content (minor).
Thanks for your attention, and remember, your first release should be numbered "1.0", and the following should all increase the Major version number. It's not me who say it, it's the logic behind the most used versioning system.
Or you can continue to do however you want and don't fucking care a single second. Because we, players, only care about one thing when it come to the version number of your game: "Was this version released after the last I played ?"
Everything else is just talks to occupy old grumpy guys like me.