It might be recency bias but maybe Advent Millenium?
I wrote it over a couple of months on my break to prove to myself I was capable of writing something of that scale. While there is some things I'd definitely go back and brush up, it is one of the first things in my life I can say I'm actually proud of. With it I can say that I've written an entire novel and have it published. I literally have a physical copy sat next to me on my desk. It doesn't feel real.
G710: Day Zero might be a close second. It was my first proper game and its incredibly rough but a lot of it came from a very raw place and I think that definitely comes across. I'd remove the wanky quote at the end though.
I think Diner 88 and HARVEST deserve honourable mentions as they were fun little projects to work on during the spooky months.
I would love to know what kind of Kaleidoverse projects people want to see next!