The reason why I don't use the GOG Galaxy is because time and time I've learned. The more software involved in playing a game, the higher the chance of something not working and interrupting when I get to play a game. This happened at Steam, only needed to happen once, and now I no longer use Steam. Divinity Original Sin was my test if steam was worth getting into...Steam failed. Mainly due to constant Steam Client Launcher downloads and updates preventing me from gaming when I wanted to.
Only reason why I even considered steam was due to the early access from Kickstarter.
Is GoG Galaxy the same way? Once I install it and use it to update my GOG games, it would be required to be running for me to play them?