Hi,
Tell me if I'm wrong, but the existing "Fullscreen mode" implemented in Elderborn seems to be a "Borderless Windowed mode" (as there is no transition if you mode the cursor between a first and a secondary screen, and no flicking screen when transitioning from windowed or to the allegedly fullscreen mode and vice versa).

I noticed this because AdaptiveSync/FreeSync is not butter smooth and I can see some stutters though the FPS reported is very high. This happens usually when games are NOT in a "real/exclusive" fullscreen mode.

Sooooo... is there some option I can tweak in a Elederborn config file somewhere to get a real exclusive fullscreen mode?

Answerinfg myself after visiting Steam Forums.

Sir Nathan The Beloved wrote there:
Silly little thing, but thanks!
Unity engine has a notorious history of despising exclusive/true fullscreen for some reason, but in your game the launch command "-window-mode exclusive" actually works as intended, making it fullscreen for reals, so thanks maintaining that functionality!

I used it in Galaxy, and it works with the GOG version of Elderborn too.
Hooray!

Thanks for the information, I didn't know this. For the pros and cons of both modes, see this comparison at the Steam forums.