What language is the game programmed in? What game engine, if any was used? Is there a campaign or just a toolbox for making stuff?

Tell me what I'm doing wrong.

Im curious to know how flexible it currently is- if it needs to stick too close from the example model or not or how feasible it is to customize it even further. Can the logic in the UI be changed at will? I know the ui can be reskinned but for example is it feasible to make a menu or character screen with way more slots for itens and such? On the trailer i get the impression the characters are in free move. Can they walk on a grid and or in turns outside of combat? How much...

How can I learn how to use this without one?

I'm wondering how many character design does the game has? Is it difficult to create stories and gameplay ? I usually play RPG Maker or Visual Novel Maker (also Game Maker Studio 2).