Dear forum readers !

I have some ideas already. Version numbers always exactly four numbers, let's say x.y.z.n.

As an example, the current Prison Architect package version is 2.1.0.3.

It seems x always equals 2, so I suppose 2 means "Good for release". 0 and 1 are for internal use only (maybe 0 isn't even used), and maybe when a package is considered RTM, x is simply increased by one.

y and z are more mysterious. While they seem to follow the usual versioning order, i.e. 2.0 > 1.3, it means there are changes considered "minor" and "major", but I don't know what makes a change minor or major from GOG's point of view.

n seems to follow a special rule, since despite being in the last position, it reflects minor and major changes as well, and seems to be the number of released packages. Hence 2.0.1.1 will never follow 2.0.0.1, but 2.0.1.2 will. And then, for example, 2.1.3.3, 2.3.0.4, 2.3.7.5. On the download page one can see "GOG-" followed by a number, I suppose that number is n.

Maybe I'm wrong however, any information is welcome !

It don't

It's so confusing that GOG has it's own versioning and it's completely different from each game's versioning. Why doesn't GOG just use the game's own version number? It would make so much more sense.

X is usually the installer version, which was 1 until 2013 or so, then it became 2. There is one exception to that, which is "The Witcher 2" which had an x value of 1 for the normal edition, then got an x value of 2 for the enhanced edition, and currently has an x value of 3 for "new" installer of the enhanced edition.
y is usually for big patches. Advanced Edition of FTL, patch 1.10 of The Witcher 3 and so on.
z is usually for small game patches. If a game's patch is just small bugfixes, but not adding content, it warrants an increase in the z value.
n is usually for small changes. A bugfix here, an image change there and so on.

So, without being sure about it, I'd say that X is the installer's version, Y is for major game patches, Z is for minor game patches and N is for minor GOG patches. Yeah. I mean, look at Flatout. It got a fix today for a major issue with Win10 (and Win 7/8 as well, depending on updates), but the game's version didn't change. It should keep the same installer number it had before, why change it? [/sarcasm]

For x i'm pretty sure it's the installer version. In this case 2. Then the other numbers probably refer to the game itself.

Using the game's version number for the package does not mean you can't add something to distinguish between changes made by GOG. They could do something similar to what Linux distributions usually do with their packages. There, packages are pretty much always versioned according to the program's version and can additionally have a package version added (which usually is just a single number). So a package would be called something like package-x.y.z-n where x.y.z is the program's actual version number and n is the package's version. n would start with 1 for each x.y.z package version and be increased by one with every new package release of the same program version.

The GOG versioning as it is now is so not obvious and confusing. Stuff like version of the installer really does not need to be encoded in the package version number. They could simply put it in their changelog or something.

Well why not have both the GOG version and the game version listed on the installer file? That would still be a lot better than some arbitrary GOG version number.

I came in to say "poorly" but, I see others beat me to similar punch-lines.

Who says it's not included? The most recently updated games (I'd guess those changed after GOG started posting changelogs) do have the game's version included, both in the game's download page (capture_1 and capture_2), as well as in the setup's details (capture_3).

Am I the only one that has no fucking idea what this is about?

Why add the game's version to a 3rd place? Especially considering that the version isn't always just a number.
The game's version is included in the setup file, and adding it to the filename would (imho) only cause confusion.
And it's not as if it's vital information you can't afford to miss, or information that must be visible at a glance to ease comparison.

So, while I wouldn't be opposed to it being added to the filename, I see no benefit from doing so.

From my library, 2 examples:

Retro City Rampage DX => 1.50 (GOG-29)
setup_retro_city_rampage_2.13.0.29.exe

But
Hotline Miami => Nothing
setup_hotline_miami_2.2.0.8.exe

What does that GOG-29 mean? And why Hotline Miami doesn't have that GOG-nn?

GOG-29 means it is GOG version 29 of the installer.
Hotline Miami doesn't have said info because it hasn't been updated in a very long time. Said info seems to be added to games that have been updated since GOG started posting changelogs.

Not really. Sometimes they would make a compatibility fix (for example for new OS versions) but the game's own version number did not change. With your idea, they would not know how to name this fix. Better have a running number as they have.

Even better have a full version history with dates and mentioning the game's own version number (good idea) and a description of what has been changed. This should be possible.
Benefit would be that you could easily see what game version this installer is related to. For example maybe you want to know if the latest installer from GOG already also contains the latest game version. Given that publishers or GOG are sometimes slow to update games here on GOG this would probably be very useful.

So I think this idea is quite good.

My proposal for a good setup name:

setup_[name of game]_[game's own version]_[gog version].exe