Finished the first game and bro, as much as the 2nd game looks better than the 1st game (we can see why Nennai felt compelled to revamp a few things now that they finally got better at designing their Leila), the first game was TIGHTLY designed. You do get to see the basis of getting "cornered" which happens alot in the 2nd game where you get overwhelmed by multiple small enemies (notably in the Abominable Stomach area) when you finally get to the Pig Farm, and how 3 livestock parasites is enough to trigger a Game Over.
That said, the first game being tightly designed also meant the first game felt smoother than the 2nd game. The 2nd game doesn't look or play as rough as Night of Revenge does, but it almost comes close.
Ultimately, I have to change my perspective on Sinisistar 2 somewhat. I've come to realize that it's pretty much the Pathologic 2 approach to Pathologic 1, wherein just as Pathologic 2 was BOTH a remake and a sequel, the same case also applies to Sinisistar 2. Sinisistar 2 basically copies the plot progression of the base game, and the Leila's design is pretty much just a taller and bustier version of Rabiane, which feels like a remake, but it's set on a supposedly different area and it's NOT Rabiane, which makes it a sequel.
One thing the first game has that I wish the sequel did though, was the final Mimic boss fight of the first game, because that fight, despite being short, was fucking hype. Seere in comparison wasn't bad, and their fight was an interesting puzzle engagement (once you figured out you can destroy his eyes, the fight was pretty much over), but it just was not as hype as facing Mimic (and somehow hotter? Why the fuck was the church bent on hunting down other nuns when they already created the hottest one?) Rabiane with a much faster paced theme to match. It was a wonderful finale. I genuinely wanted MORE.