Despite it's length, The Black Plague makes a fitting sequel (and ending) to the even shorter Penumbra series.
The Black Plague continues the story of Penumbra from when you were "killed" but apparently just knocked out at the end of the first game. Dazed and confused, you find yourself trapped in a small room, comfortably lying on a soft bed (not a bad start :3). However, hopes of safety go completely out the window once you start to hear some horrible screams coming from a nearby room. As you've probably guessed, whoever (or whatever) "invited" you into the Shelter probably doesn't plan on serving tea anytime soon. What you do know is that you have to get out of there fast! And from then on, it's classic Penumbra rummaging through drawers, messing up electronics, and solving puzzles.
Just as I've already said, gameplay in this one hasn't changed much from the original. You still get to navigate FPS style with the keyboard, and pick up and whack things around with the mouse. Some things can still be picked up and stored in your inventory, and others you'll just have to find an immediate use for. The defining factor of the game, the hand interface, is better than ever, now fitted with a visible crosshair marking the center of the screen. Frictional Games has certainly done well for our convenience. You'll also be happy to know that puzzles still require much hands-on interaction. There's much more crate pushing, lever pulling, object dragging, and valve turning to be done in this sequel since it focuses primarily on the puzzles and the story while trading away the combat factor. An important thing to note is that this time you won't find any weapons lying around. ('omgwtf1!? so, how do I kill stuf!f?') You won't be killing things with fervent whacking this time. For the most part, you'll be running for dear life while navigating towards the closest door, since that's the only way to escape these predators. However, don't be too disappointed that you're now reduced to being a running, screaming sissy-man. Surprisingly, this makes the game even more challenging (and more thrilling) since you'll be observing enemy movements more closely, and planning your moves well. This way, you're sucked even more into the game. It's like playing 'Silent Assassin' -- minus the 'Assassin' part. If that kind of stuff bores you, the option of running in and hoping for the best still stands most of the time. Plus, there's still some action once you get to the 'bosses'. These are the enemies you'll be forced to face off with. ('uhhh, no weapons?'') Since you're empty-handed, you'll have to use your surroundings to your advantage. And this can actually get quite fun. And that's pretty much it for gameplay.
Graphics-wise, Penumbra has gotten better with added blur effects, real-time shadows, some smoke here and there and better textures and filters. But overall there's nothing too special about the graphics considering the generation of games it came out with. But, thankfully the visuals don't disappoint considering they still are quite nice and you'll be in the dark most of the time anyway.
Sounds are as great as they've always been. And the ambient noises are still as hair raising (or even more than) as with the Overture. Frictional does well with the voice actors in this one, too. Though your character's voice may have changed and most will probably prefer the original voicing, the voice-acting from the other characters are just splendid. As much as you'll miss Red's rambling into insanity, you'll have a couple of friends to talk to this time. One is a girl (a survivor?) who you'll be communicating with using web-cams of a sort. Sadly, her cam's busted so you'll be talking to static as she tells you how much you look like sh*t. But who cares? Cause she's got a really nice voice and a British accent to boot. Throughout your endeavor her voice and the promise of finding answers will be your primary drive to finish the game. And the other character you'll be hearing from? I'll save that for you to find out. Let me just say that you'll either love him or you'll hate him. I just found him annoying, even if he does cracks a few good jokes once in a while.
That's been quite a long review, but I made that for both the first and the second Penumbra so please bear with it. Overall, Penumbra's been a nice experience with it's well-conceptualized storyline, well placed visuals and solid, and innovative gameplay. Compared to Overture, TBP is comparatively shorter but makes up for this with answers and the completion of the story. It's a game best recommended for those accustomed to dark/horror genres or those looking for a dose of fear in their gaming. This game is not for the faint of heart... seriously. I'd like to comment however the series has been shorter than I could have wished. Given the story and all the floating questions, this could have easily made it to a 3rd installment. But, well, it's done and there's nothing left to be done about it.
Edit : So, Frictional Games went against their original decision (and better judgment) and made a 3rd. Nevertheless, skip that one, please. It doesn't do justice to the series. Be content remembering Penumbra as you see in The Black Plague.