Is this a continuation, a remake or what?

It's a spin off story that focused on Solitaire! If you are wondering about the timeline then, it's way before the main story start

Thank you! Do you know if the order in which one reads makes any difference? Like, can I read this by itself? And if I decide to read the other after, will I be too spoiled by then?

Dw about it! they won't be much of spoilers. I mean.. there's a tiny hint but it's not too noticeable