All three games in the Penumbra series feature eerie, unrelenting spaces within which you can find genuinely interesting scenarios and, from time to time, actual frightening encounters with otherworldly forces.
"Scary games" have long been a mystery to me. I find some games scary that most people don't; traditionally, though, scary games are often less scary than they are annoying. When I play games like those in the Resident Evil series or F.E.A.R., I'm less scared than I am wary, tired of knowing that I will be "scared" by sudden noises or sights, and the possibly explosive, sudden appearance of enemies.
I do not think of this as being scared. I think of it as being surprised, taken unawares. Being actually frightened, and jumping a bit because you didn't expect that ghost girl to appear out of that pipe (and why would you?) are two very different things. Obviously, a lot of gamers are happy to accept the startles even as they hope for the true frights. That isn't to say that some games don't try to do both, or even (amazingly) emphasize the latter. The Silent Hill and Fatal Frame series put a lot of effort into creating a foreboding, relentlessly unpleasant atmosphere and environment.
Recently, Siren: Blood Curse did the same for me, but none of these games accomplish what Frictional Games' Penumbra series has accomplished. These games, using relatively low production values and little visual or stylistic flare, create eerie, unrelenting spaces within which you can find genuinely interesting scenarios and, from time to time, actual frightening encounters with otherworldly forces.
There are three games in the Penumbra series: Overture, Black Plague, and Requiem. All three games are thematically consistent, in that they are centered on a mysterious and dangerous research facility and cave network, deep beneath the ice of Greenland. The games at first seem like slow, first-person survival horror games. At first glance an observer would see typical survival horror elements on display, like wandering around, picking up items, and escaping scary dogs. You also play an unlikely hero, an academic in way over his head amongst all of these otherworldly occurrences.
Where the Penumbra games aren't like typical FPSes is in their primary interaction mechanics. At certain times, the player's reticule becomes a hand (like in Myst), and the player interacts with the object before them. Instead of simply activating objects, players interact with them in a realistic, physical way. To open doors, the player must make a pulling or pushing motion with the mouse, and the door opens with the appropriate force, given the violence of your action. Yet the game is still a FPS for all other purposes, allowing the player to move, jump, run, and crouch like any other shooter would. It takes two genres -- shooters and adventure games -- and melds them together.
Uncharacteristically for a puzzle game, Penumbra also has a stealth mechanic of the kind that you'd probably be more familiar with if you'd played a sneaking-based FPS like Thief (or even Splinter Cell). After a few seconds of standing still, your night vision will kick in. You'll be harder to spot in this mode, and you'll be able to see your enemies. Considering your character's night vision is wretched (and personal light sources alert enemies), your visibility and general conspicuousness become constant worries.
The formula I've just laid out is incredibly effective at making one feel claustrophobic and isolated. I was always afraid of parts of Myst, but I never had to worry about scary monsters coming after me. In Penumbra, the threat is really there. True, the game will often give you space and time in which to solve puzzles unmolested, but it also tasks you with solving puzzles under the threat of attack. There's nothing quite so frightening as plodding around (you are one slow explorer) trying to find the right cog or tape, knowing that dogs, spiders, infected humans or giant worms are stalking you.
Likewise, your introduction to the series' central antagonists (the overly evolved worms) comes in the form of aggressive clanging noises, and then a sudden confrontation over the splinters of a shattered door. The fact that these monsters are practically impossible to kill is not a new idea in survival horror games. Enemies who cannot be killed the first few times you encounter them are old staples of the genre. You know you'll have a chance to douse them in acid or drop them down a mineshaft or something, so for the time being they are annoyances.
What struck me about Penumbra's relentless enemies is that they can be defeated, in a sense, by using the tools and skills the game has taught you. When you are first chased by the dog, you can hide atop tall objects to stay out of reach. If you prepare yourself by barricading a door (on both sides), then you can escape the dreaded worm, initially. The game prepares you to use your environment to solve every problem you encounter. Thus, when you must use your environment to trick or defeat enemies, it never feels tacked on or forced. It's how you survive everything.
I'd be remiss if I didn't mention that the combat is absolutely awful. In an awkward parody of Wii control schemes, you'll use your mouse to swing items back and forth, bludgeoning enemies. It's unwieldy and makes you want to avoid conflict at all cost. Still, I'd argue that this is in keeping with the game's tone: you are an academic, a man unused to exertion, let alone combat.
The combat is mostly left out of the second game, with stealth being your primary defense against the eerie infected you encounter. The final chapter, Requiem, does away with all enemies. Instead, death can be brought on by environmental hazards. This is where the series falters, and loses all of the tension and fear that was so gripping throughout the first two installments. With no skulking threat in the wings, there's no reason to fear the game's various dark settings. Requiem takes the vicious promise of swift death that made me afraid to blink in the first two games and cleanly removes it. You're left with a pretty good physics puzzler, but it's a shadow of its former self.
The Penumbra series should be recognized for its achievements in immersive world creation and its ability to trap you inside a very real and dangerous physical space. I would love to see more games in this genre, especially because the more conventional survival horror genre is already being twisted in its own new direction. I've yet to see a game that tops Penumbra's ability to scare, and I'll probably have to wait for Frictional games' next offering to relive this kind of experience.