It was Dec 12th, 18 days ago, not 180 days ago, that he teased the pic of Lin. He had mentioned something kind of hinting that he might continue with another character before that.
2 days ago:
"There was a game called F-IST, where you fight girls in first person, and I thought, "Wow," but unfortunately there was no reverse ryona element. The game was fun though. "
"So, inspired by that, I made a test game. It worked better than I thought, so I'm considering whether to make a continuation."
(replying to a question about it:
"It will be different from UFG2. This is because the production tool is MZ, not RPG Maker MV. It is undecided what kind of thing we will make. We are undecided about whether we will make a continuation in the first place. "
It's kind of hard to tell, but it looks like he likes whatever he programmed that video with.