The lack of being given even a bit of a layout of the mansion in either a rudimentary map being shown at the start, or even a text description of what rooms you'll need to enter kinda sucks, even if it's probably somewhat intentional with the story. Mansion itself is pretty linear, not bad given the lack of informed layout, but also lacks the fun of "this route is faster, but riskier" options if it was less linear. Also kind of ruins the realism since it becomes more obvious it's a video game location instead of something people could've realistically lived in at one point (especially with how wide some rooms are.)
There are corners that realistically should cover Maria from view, but don't. Not really a bug I think, but perhaps care could've been given to allow the guards not to see her if she was in those spots. Guards themselves rotate in a rather unorthodox way that I think was done so players couldn't hug them as easily but it doesn't look that great, though it's generally forgivable, just looks a bit silly. Lack of view cones was probably an intentional choice, but annoying since you just have to guess if they have side vision or not (they do!)
If you make a longer version/future one perhaps consider having preds and prey species have different view cones so players will have to ID the species and plan accordingly (general differences between them would be fun too, like Lizards taking more bullets from lower powered/non-AP guns, mice/rats sensing vibrations and detecting the player walking behind them, or rabbits/bats being able to hear suppressed shots.)
I assume there's at least 2 endings but are there more than that for getting 0 kills/0 alarms? Would like to know before I try those runs.