If you download the latest version (currently being Chapter 1 - Episode 3 (Part 1)) you have access to all the previous parts of the story, plus the Emma solo ending all in one archive.
The solo ending is an alternate ending, not necessarily canonical, but it's a worthy experience. To access it you have to choose the option to fullfil the promise that the MC made with Emma. This option opens up after the raid to Hera's home.
I advise to save before choosing that option if you also want to see the other half of the story.