Luanti is a credible replacement option for Minecraft single-player

Steam has a "Go Offline…" options for pretty much that. Indeed it sucks that you have to do that before you go offline, but it sounds like a good idea with your setup and just switch to online occasionally to update.

Furthermore it depends heavily on the games, not on steam. Some steam games work without the steam client, though for some of those you have to fiddle around or execute different binary.

Steam works fine for me offline, though I can't speak to all the games - what are you running into with it?

I hear you on Minecraft, though...

I don’t think it’s ironic, it just doesn’t say the quiet part out loud. Everything just works if they control the entire ecosystem, so if you want ‘sophisticated’ let us control everything and it will all just work.

Simplicity is easy to pirate though.

If the product is a program that executes 100% of its functionality on your computer, it is impossible to make it pirate-proof. Even if all the functionality is client-side and the server is used only for authentication, it can be pirated.

The only way to make a program pirate-proof is if it runs on the server with a thin client.

That being said, some products execute on the client. Therefore if they want to prevent piracy, the only thing they can do is security through obscurity. That is, make it as complex as possible so the pirates take as much time as possible to reverse-engineer it.