Looks really cewl! I almost bought it from GOG until i realized it's Windows only :( Any plans on releasing a multiplatform version?
So i bought the game on GOG anyway hoping it to be released for mac soon. Tho i got it working on Mac for now :)
What i did is use innoextract to get the gamefiles from GOG's installer and wine to run the game. Both tools can be installed easily with Homebrew. Enter the following commands from terminal to do so:
brew update
brew install innoextract
brew install wine
After that is installed you can use the following command to extract the installer (Please note that the actual installer's filename could be different):
innoextract setup_mainlining_1.0.02_\(9587\).exe
Cd into the extracted folder and then the 'app' folder where the game files are located in and enter:
wine MainliningGame.exe
Have fun ;)
Above steps (except for the Brew part) probably also work on a linux machine. Tools like Wineskin or the likes may make things easier but above steps feels natural to me since i'm a terminal fan/nerdboy.