Game compression could bring it to smaller size, if game upscaled images instead of requiring minimum of 1920x1080
You can use higher compression ratio for images used in this game. My compressed 17.2 is around 2.8 GB
And?! I've seen some project were the difference was much, much more, cause the image used were PNG (which we both know, could be compress quite a bit, if you want and don't care about that little quality lose that you most likely won't even see). The ratio is around 4:11 or, if we use your numbers, 3:11. Where other games achieve a much higher compression ration from the same compressor.
Thus, the 11 GB of this game leads to either a much higher image size or have a much larger number of images, what often also means, the game itself is much bigger.
It is a comparsion. If the size of the game would be much lower, eg. 1 GB or less, then you have "bloated" image, that are useless if you are not the Louvre (or any other museum).
Also, as I've written in the past, this game could also be compressed to less than a few MB (plus the whole Ren'Py base setup, who is already ~130 MB). Just remove the image and sound and leave the text to be there.