Does anyone know if there is any chance of a Mac version in the near future (offered on gog)?

This GOG version of the game runs percfect with wineskin.

You have to install the gdiplus.dll from Wineskin itself and install de game.

I have looked, but cannot find how to do this. Could you please provide instructions for which Wineskin build you used, and how you installed gdiplus.dll into it?

It's so easy:
1- Download Wineskin Winery
2- Copy the App to your Applications Folder
3- Open it and install an Engine (wine 1.4.1 recommended) and a Wrapper
4- Create a New Blank Wrapper (Name it as you want, the name of the game will be the best option)
5- Install what it asks for (it takes a minute to load)
6- Open the Wrapper (/user/Applications/Wineskin/)
7- Advanced
8- Go to Tools and Winetricks
9- Look for gdiplus.dll and Run. It will go to cnet to download the dll.
10- Place the downloaded file in the folder it tells you (Users/user/Library/Caches/winetricks/gdiplus
11- Run again Winetricks
12- Close Winetricks
13- Go to Install Software
14- Choose Setup Executable and follow the usual installation steps as a Windows program.

Hope it helps!

(if anyone finds how to do the same with La Mulana, I'll be happy to know how to do it)

Excellent instructions! Unepic runs properly. If I learn how to run La Mulana, I will let you know.

Thank you for your step-by-step instructions. :)

May I ask how you found out which dll was the one necessary?

Well, wineskin asks you for it.

Anyway, the missing dll is the one that GOG installator needs.