So this is a timeline where Letty solved the Unending Winter incident? That's pretty neat.
It's a VN so here's what I thought of the writing: putting it bluntly, I didn't feel convinced by what I think is supposed to be a Letty-Sakuya ship. The game clearly shows they just haven't met before and Sakuya gets on the way back defeated too (one playthrough of PCB from stage 1 to meeting Yuyuko lasts a little less than 30 minutes, the more you know), and now Letty's kinda warmed up to Sakuya?
So Letty becomes a PCB protag and shoots down the bosses (as I said, I think it's a pretty neat idea!), but what's up with her blushing red every five minutes (even in front of characters not named Sakuya)? Is she OK?
And then Letty claims spring back and returns, and meets Sakuya again. And I was like "Why is Sakuya freaking melting in front of Letty too?", they haven't even spent more than 5 minutes together, and now Letty has to go and returns next year - is this really happening?
tldr: not convinced by the ship because Letty and Sakuya didn't even start building a relationship.
The other aspects of VN, well, the character portraits are decent (also Lily just has something more akin to a sprite - she never had an official portrait after all. Nice touch, made me smile!), but the highlight surely are the arranges. There's an impressive amount of them for one person to make in a month, that's highly commendable.