I do not want to install the GOG Galaxy spyware, how can I install games when even GOG says I have to do it through Galaxy.

Registered 2013 and you don't know how to download games?
Why bother explaining it.

You can use the main web site and sign in to download and update your games but only to play offline

It's not spyware. It has telemetry, and I do wish GOG would give us the option to turn it off, but it's not even close to what other clients collect.

If you absolutely can't even give Galaxy a shot, there are the offline installers that you install via the Games section under the drop-down menu when you hover over your username. That's one of the beautiful things about GOG: with very few, minor exceptions, you can use the offline installers and play completely without the client.

The nice thing is that if you decide you want to use Galaxy down the road, you don't have to do much to link your games into Galaxy. The even nicer thing is that if you decide you don't want to start up the client to play your games every time, you can still play the game, you just have to go to the game folder and make a shortcut to the executable (instead of the default shortcuts that Galaxy places, which are set to open the client with the game).

Just learn to read. Because we already know that you can write ... stupid things.