Change the game version within the game

Hi, I didn't know how to write a good title for this post, but here it is:
I want to make it possible for players to play old versions of my project but without having to create a launcher for it (similar to what Minecraft does).

An architecture similar to what Minecraft does:
You select to play the desired version, then the game downloads the selected version that is stored on the server directly in the game directory on your machine, and you are ready to play.

But the problem is that I don't want to make a launcher for this (and it wouldn't make sense to have a launcher if I wanted to recycle that idea for future larger projects that would be ported on platforms like consoles and streaming).

Can you do that within the game itself? Basically at runtime?
Sure, I know I could download all versions of the game and make them available to play at any time, but wouldn't that be detrimental to the size of the build?

 

Not really.

On windows platform a process cannot delete its own executable. Now, you could try to work around that, but you'll be fighting the engine you're using, and you'll need to figure out how to move the old files out of the way while the game is using them without breaking the update process.

In my opinion, It isn't worth it.

The best way to do it is via a launcher/updater program.

 

How about using steam? Its not supported to downgrade (but you can do it with some skill) and you can have beta branches etc

 

It can be done at run time to certain extent. But much easier would be, if game is designed to be modular and in moddable faction. Then just loading relevant modules.
Or, having mini updater app, which executes when game launches, checks for updates and load them, before game starts. Alternatively updater app waits to close the game and then updates files.
But informing player about the update within a game, would be first step. Give them link and allow to download manually, what requires. Downloading full game is often simplistic mouth, to implement.

 

I even thought about using P.A.T.C.H and talked to the plugin developer, he says that "maybe it's possible in some way using the source code". I'm still thinking about it.

I really wanted to avoid having to work with launchers.

Wait, really? I didn't even know it was possible.

Yeah, I am working to make my project modular, in some of my posts you can see my interest in making the game easy to be moddable and fully modular to facilitate various tasks. Also, to what extent could this be done at run time?

Thanks, I will think about it and try to figure out how to implement.

 

To the point, you decided to update the core app, which will require replacing file and restart of the game.

 

Any in app solution will be more difficult than doing so with a launcher. Though it would be pretty simple to design the launcher so it doesn't pop anything up (just launches the main app immediately) and you could add an interface to your main app to tell the launcher to upgrade/downgrade the main app. So it would function to the user as if the main app handles it, even though it is really the launcher doing it all.

 

Well, I think all of that clears up all my doubts
Thank you all.