Is there any difference between GOG's and Steam's version of this game? Reading the requirements, it's 2 GB free storage space on GOG, while it's 3 GB on Steam. I'm no expert, so I wonder what's that extra giga for. I'd like to buy the game here on GOG, but the whole "second class citizen" matter leaves me hesitant.

One of the developers answered me on Steam's forums, assuring me the versions are the same. They recently managed to reduce the storage space required to install the game, but the related info hasn't been updated on Steam's page of the game. That's all!