Ok, no problem. Easiest fix for people that only want to play single player campaign. Delete the shortcut on your desktop. Then navigate to your usual GOG install folder. Mine looks like this. (C:) GOG Games, open, open AvP Classic folder, right click AvP_Classic, then create your own shortcut. You can also create your own shortcut from the Launch Aliens vs Predator Classic 2000 shortcut too. Now you may still want to check for updates and do them manually yourself. Not like this older game will get too many though.

Seriously, did you read anything about the galaxy client so far? This is going to be completely optional. Furthermore this is a beta test to test the multiplayer backend of the galaxy client. How can you expect to not have something galaxy related on your PC if you choose to install it?

GOG released this game for free so that people will use the client and test their MP infrastructure. I'm sure they won't care much either way and I hope you enjoy your game, but it really would help them out to have another computer try it out.

As for the client-bundle, the game will have a different download after the beta is finished. It will include just the game and not the client. The client will be completely and utterly optional forever (so they say anyway).

And I'm with you. All of these clients is annoying. Origin and Uplay most of all since they're just one-publisher clients. But Galaxy will bring back MP functionality to a bunch of games and be completely optional. So I'm 100% on-board with it.

Oh, and one last thing. The updater isn't for AvP so much as AvP+client. GOG is using data to make the MP client better, so the updates are delivered to the beta testers to test their new code out. That's all that does. O highly doubt you'll find a major update to AvP.