Here you can find some useful info about gameplay, language, save file location etc.
How to start a new game (save file location)
Your save file is stored in the Windows AppData folder:
You can delete this (or just rename the folder) and the game will act as though you are launching the game for the first time and create a fresh save file.
The game's text (including dialogue, short stories, etc) will be available in all 14 languages. Devs will update the store page later.
It's a visual novel (more specifically, a kinetic novel) that is rendered in 3D and separated into chapters. After each chapter, you get to explore the game world in first-person and unlock side content, which is essentially just short stories set in the same world, before moving onto the next chapter.
How to continue from second exploration area
You should be able to return to the first floor and use the tablet to advance. The staircase is blocked to start with. There's a memory at the top of the staircase that, when unlocked and read, will allow you to use the staircase to return to the first floor. Note that the memory in your path requires no fragments to unlock, so you can't get locked out of progressing due to not having enough fragments.