Despite have a basis in being a visual novel style, I was pretty invested throughout. The sound design was quite good in both the music and effects, and the artwork was quite complementary to them as well. Especially so since you spend much of act 1 looking at into a dark cave, with only the difference being her 3 eyes opened/closed, and a claw coming out occasionally. The death screen is also nicely done in how it comes out, very good visual feedback.
The story overall is a bit light being taken from what we know of SCP so far, but really I was far more invested in the dialogue and discussions with 682. I really felt like this nailed her personality down from when she is talkative to being annoyed, though it did feel there were a few times the lead overstepped his boundaries a bit much to be believable. Her having a slightly sadistic/mischief streak along with her disgust/irritation and predator/prey view for others was very on-point, but I especially like that the first time she opens up is when the lead absentmindedly implies he could die by her hands and she takes notice. I honestly forget I even was playing an H-game because she was so interestingly *alien* to speak to.
On the downsides in the demo, waiting didn't seem to do anything besides sometimes let 682 finish her food. Giving her food I had to get a feel for "how much" she wants before receiving dialogue, but it felt a bit save-scummy finding that out. There was also an odd bit on the last (2nd to last?) day where I got the same banana dialogue again instead of the other one I to reload multiple times to see.
I also admit like a previous commenter, I came for a monstrous lizard gf, and saw an anime monster girl which is pretty disappointing, day ruined, etc etc. You've mentioned you'll explain why she looks like that in the next update, but I do hope we get to see the girl monster lizard at some point since Mal0vent shows you can keep the skull and still have an attractive gal - a lot of nice 682 artworks show that as well. I am still interested based on what I saw, so I wish you good luck and will follow along to see what's next then!