So in order to unpack the game files, you have to... install 7zip (or any other unpacker that supports SFX self extracting archives), right click the only EXE file in the game folder and select the "Unpack to this folder" option. You'll end up with the game's executable, having "STEAM" in its name, data.win file (basically, game contents), option.ini and set of OGG files. Now you can remove the original packed exe and rename the unpacked one to have the game permanently unpacked. Have fun.