Finding hours played in Galaxy
Open GOG Galaxy, select a game in your library, and its details panel shows time played alongside the last-played date. Galaxy's integration plugins can also pull playtime from connected accounts such as Steam, so a game you own in several places may show a combined figure.
What Galaxy has never offered is a first-class way to sort or total the whole library by hours. It is a long-standing community request. You can build custom library views with filters and tags, but ranking every game by time played is not among the built-in sorts.
The DRM-free contradiction
GOG's defining feature is that you can download an offline installer, install the game, and run it forever without a client. That is also exactly the situation in which Galaxy records nothing. Double-click the game's executable and no time is logged, because the client was not involved.
Plenty of GOG customers keep Galaxy uninstalled on principle, or use it only to download. For them the store's own playtime figure is permanently near zero regardless of how much they play.
Over-counting is a real complaint too
The opposite failure also shows up: sessions that keep accruing after you stop playing. When Galaxy hands off to another launcher, or when a game exits to a separate configuration process, the client can keep a session open longer than the game actually ran. Users have reported both missing hours and inflated ones, which makes the number hard to trust for anything precise.
A tracker that does not care how you launched it
PlayCounter watches Windows processes rather than launcher events. A GOG game gets timed identically whether you started it from Galaxy, from an offline installer's desktop shortcut, from the game folder, or from a portable copy on an external drive. The session begins when the recognised executable appears and ends when it exits.
That makes it a natural fit for a DRM-free library: you keep the freedom that made you buy from GOG in the first place, and still get a playtime record. Everything stays local, no account is required, and the app is MIT-licensed and open source, which you can verify yourself.