Pygmalion_4678: "Agatha Christie - The ABC Murders" got a major update on Steam:
"Hello everyone,
Today we are publishing a major update for Agatha Christie – The ABC Murders.
With this update we reworked several aspects of the game:
· A brand-new "Brain cells" interface reinforcing player’s immersion
· A smoother gameplay to provide a better experience
· Now 4K compatible
· Framerate increased from locked 30FPS to 60FPS
· Addition of multiple tutorials to guide players
· New lighting effects
· Reworked sound design
· New anti-aliasing more on par with the artistic direction of the game
With those new additions, there is no better time to rediscover one of Hercule Poirot's most famous investigations!"
Source Hi
From what I read, GOG can be somewhat slow to approve new updates.
Since this update was released just a few days ago, maybe it's GOG that's delaying the update, so I'd wait a little more before reporting the game in this thread
But just in case, I sent an email to the developers asking about the update