Hi Geofferic
We've now added the subtitled version to the installer, so if you download it again, you'll have the option to choose the subtitled version or the full audio version to install. In hindsight, we made the wrong decision to only provide the full audio version, we're sorry for this. We'll try to expand our product descriptions to include this type of information in the future.
I hope that now you'll be able to enjoy the game =)