petitmal: Age of Wonders series; Europa Universalis series.
Just to name two (I found more) of the titles published in Windows as well as Mac format - available as such at least on Steam and in the Humble Store.
These games are Windows exclusive here on GOG. Why?
Any ideas?
I'm a Linux user, welcome to my world.
As a software developer, I opted to focus on browser development for my client-side experiences, because I can't be bothered dealing with an entirely different environment for each platform.
Honestly, I don't know why game devs don't look for the most cross-platform solution they can find (especially when they don't require bleeding edge graphics)... when I see a game with graphics that look like they were from a decade ago or older and it doesn't run on Linux, I feel like smacking the devs for being plain lazy about it.
It would really help if Windows didn't have such a strong monopoly on the desktop (atm, they are like Internet Explorer in the browser world 15 years ago with their ~90% market share), though, I'm not really sure I'd want users to switch to Mac either (overpriced hardware really).
Atm, I'm strongly considering just forking the price for a Windows license and running Windows in Qemu/KVM with gpu passthrough. Unfortunately, KVM doesn't support a egpu setup yet with gpu passthrough, but my built-in graphic card is still powerful enough that it would allow me to play 95%+ of games in the foreseeable future. I just need to reserve a day to set it up.
That's a possibility in the Linux world (and the main pain free way to be able to play most games without a dual-boot in the foreseable future imo). Not sure about Macs as I know Apple is more control-freakish about what they'll allow, but it might be worth it for you to look into it.
Just google "gpu passhtrough Mac" and see what you find.