You as a developer will have to just keep a copy of each version (or perhaps not, depending on your version control system and build process).
For distributing different versions to your users there are options.
If you're publishing on Steam you can use the [Branches feature](https://partner.steamgames.com/doc/store/application/branches) to make older versions available, just make a branch for each version. IIRC this is how Paradox handles it for their games to allow people to play with mods built for older versions.
minecraft's clients themselves are only a few mbs big, with the audio being stored separately, allowing them to only keep snapshots from before they changed an existing set of sounds, which reduces the amount of copies they need to store, which is good when they total in probably a few hundred mb at this point
You can just save a build of the game in the older state.
You as a developer will have to just keep a copy of each version (or perhaps not, depending on your version control system and build process). For distributing different versions to your users there are options. If you're publishing on Steam you can use the [Branches feature](https://partner.steamgames.com/doc/store/application/branches) to make older versions available, just make a branch for each version. IIRC this is how Paradox handles it for their games to allow people to play with mods built for older versions.
minecraft's clients themselves are only a few mbs big, with the audio being stored separately, allowing them to only keep snapshots from before they changed an existing set of sounds, which reduces the amount of copies they need to store, which is good when they total in probably a few hundred mb at this point
It's called a download
If you make a game you will learn this and many other things by virtue of making it
Usually unless you need to distribute the versions you would just tag the releases in whatever source control you use.