I'd say this second entry in the series is, overall, a fair bit better than Penumbra: Overture. There were a lot of irritating gameplay decisions in Overture (terrible combat, horrible UI when using tools, improperly contextualised 'hints') which are straight up removed in Black Plague. But it does at times feel like the devs didn't really make any attempt to replace these removals with anything. Long story short, Black Plague is much more of a walking sim than Overture or other games in the genre like Amnesia. This isn't necessarily a bad thing, I definitely prefer it this way than to how Overture felt the need to pepper the map with dozens of copy of the same two irritating enemies, but it does hurt the immersion a bit in Black Plague when it isn't very good at hiding just how infrequently you are in danger.
Aesthetically I'd also say Black Plague is an improvement on Requiem. The overall theme is more interesting (to me at least) and much much more varied; gone are the endless carbon copy mineshafts of Requiem, and the different parts of the facility in Black Plague actually feel like distinct and different places. I also found that the part of the Penumbra story told in Black Plague was somewhat more engaging than in Requiem. Requiem seemed to be focused on desperately coming up with reasons that the player character got himself into this mess to begin with (and frankly not coming up with many good reasons at all...), whereas Black Plague is about him trying to get out of it and is inherently more relatable. There are also more characters and generally more moving parts to the story, and one of the plot twists caught me completely off-guard in a good way. I was unsure about Clarence at first (the character you spend the most time interacting with), but I grew to appreciate his presence over time; he can be pretty annoying, but he gives this game a certain life and character that was less present in Requiem.
Black Plague, however, loses some points for me for its ending. It sucks. The last challenges / trials / whatever you want to call them are absolute nonsense, and completely tonally dissonant with the rest of the game. And this extends to the ending of (this part) of the story as well. Everything just becomes a bit farfetched and silly right at the close, and it definitely lost me a bit. But right up until the tonal shift (which is very near the end) I found this to be a pretty good time. It's another 'Amnesia with less stuff in it' game, but with almost all of the actively bad stuff from Overture stripped out, and as a consequence I feel I can recommend this one somewhat more.
Aesthetically I'd also say Black Plague is an improvement on Requiem. The overall theme is more interesting (to me at least) and much much more varied; gone are the endless carbon copy mineshafts of Requiem, and the different parts of the facility in Black Plague actually feel like distinct and different places. I also found that the part of the Penumbra story told in Black Plague was somewhat more engaging than in Requiem. Requiem seemed to be focused on desperately coming up with reasons that the player character got himself into this mess to begin with (and frankly not coming up with many good reasons at all...), whereas Black Plague is about him trying to get out of it and is inherently more relatable. There are also more characters and generally more moving parts to the story, and one of the plot twists caught me completely off-guard in a good way. I was unsure about Clarence at first (the character you spend the most time interacting with), but I grew to appreciate his presence over time; he can be pretty annoying, but he gives this game a certain life and character that was less present in Requiem.
Black Plague, however, loses some points for me for its ending. It sucks. The last challenges / trials / whatever you want to call them are absolute nonsense, and completely tonally dissonant with the rest of the game. And this extends to the ending of (this part) of the story as well. Everything just becomes a bit farfetched and silly right at the close, and it definitely lost me a bit. But right up until the tonal shift (which is very near the end) I found this to be a pretty good time. It's another 'Amnesia with less stuff in it' game, but with almost all of the actively bad stuff from Overture stripped out, and as a consequence I feel I can recommend this one somewhat more.