A is for Amnesia: The Dark Descent
SPOILER ALERT for all of the games I'm discussing in this series, by the way.
In terms of aesthetics and tone and plot devices and setting and all that, Amnesia is a pretty obvious choice in terms of dark/weird fantasy inspirational material. I probably don't need to go on at length about the look of the castle, the game's horrifying torture-based alchemy, the Lovecraftian elements, the monster design, etc. If you dig that kind of stuff, Amnesia will probably give you some obvious inspiration on the "fluff" front.* But how about the mechanics, the "crunch?" Anything under the surface we might want to consider including in our tabletop games?
Well, one major lesson in Amnesia (and from what I hear, in its spiritual predecessor, the Penumbra series) is that the monsters or enemies in your game don't have to be conventionally "beatable," at least not in straight-up combat. Speed, stealth, and cunning are Daniel's only real defenses - I think the implication is more than just "Daniel is kind of wimpy and these monsters are big and strong, so Daniel doesn't stand a chance in combat, thus there's no attack button." Considering the line in the beginning of the game about Daniel being young and fit and more than a match for the old man he needs to kill, as well as all the heavy stuff he lifts throughout the game, I don't think this comes down to a simple matter of strength (or even martial prowess - the monsters aren't exactly kung-fu masters). The monsters are supernaturally invincible, unkillable. They're not cannon fodder, existing to MAYBE drain some resources and then be mowed down heroically. They're there to put pressure on the player in a different way - you have to know your hiding spots and your exits, or else be able to find them quickly, and you have to exercise caution and self-control with your light and noise levels. Besides, even if Daniel could take out some random shuffling horror with a lucky barrel toss or something, the Shadow is coming for him. Fighting that would be like trying to fight a tornado.
This kind of thing isn't unheard of in tabletop games. This is old hat in stuff like Call of Cthulhu, in which straight-up combat against monsters is almost always a bad idea unless you want to die
And the monsters don't have to be completely immune to damage or whatever - I don't think you should railroad the players into only being able to deal with a monster in one highly specific way, but you should be able to limit their options to make things more tense and interesting. Narrow the range of options while still allowing flexibility. The classic werewolf is a good example. Let's say it can ONLY be killed by silver, and there's no silver for miles. The low-level party of PCs isn't going to be able to stand toe-to-toe with this thing, but that leaves many options. They could try to avoid it in a million ways, with stealth or distraction or just by beating feet. They could try to come up with an alternate way of taking it out instead of "killing" it - drop it down a big pit and bury it, or trick it into stowing away on a ship and then sinking it, so even if it's not dead it's at least busy for a while. They could try to bargain with it or charm it somehow. They could travel to a different region and get some silver to even the odds. And once they get that silver, there are so many choices in how to USE it. Bullets? Blades? Molten metal?
But you know what? Why not throw something actually unkillable at the players at some point? Not as a cheap "gotcha!" to rack up an easy TPK, hopefully - even the killer bunny in Monty Python and the Holy Grail had plenty of warning signs for the knights to fail to heed - but as an interesting challenge, and as something SCARY. Make your players feel harried, hounded, preyed upon. A monster like this can add even more time pressure than a limited supply of torches and rations if you make it pursue the party slowly but implacably. Go all Terminator on their asses. Their ingenuity in survival tactics might surprise you.
And that whole unstoppable-force-of-doom-coming-for-your-ass thing reminds me of another aspect of Amnesia that could work wonderfully in D&D: The only way out of the dungeon is THROUGH the dungeon. The old D&D video game Eye of the Beholder did this, too, by having the dungeon entrance collapse behind the party once they enter. You can have multiple ways out, of course, and I think you should certainly make the dungeon itself non-linear in design so the players can make meaningful choices about what obstacles are worth contending with and how they should be defeated, but preventing any kind of easy backtracking out of the dungeon can be a great way to build a sense of claustrophobic terror, I bet. Especially if your route back isn't just cut off by a passive obstacle like a cave-in, but by some kind of crawling god or something.
In one of our D&D 3.5 games in college, my friends and I were playing through Rappan Athuk, and you know what kept on working its way into our conversations? A supposedly invincible monster made of dung, of all things, on one of the upper levels. It wasn't particularly dangerous, since it was easy to avoid, but due to a curse we couldn't leave the area unless we purged the dungeon of all evil, and guess what? "Dungy" lit up when Detect Evil was cast (or at least that's how I think its alignment was discovered, since I wasn't there for that particular moment). It because this major puzzle in the back of our minds throughout the whole dungeon: how do we kill this invincible piece of shit? Unfortunately, we never got to finish that campaign, but I bet we would have come up with something cool if we had enough time. "How do we deal with Dungy?" was our great mystery. It was our great brown whale.
Amnesia is also interesting because of the moral compromises Daniel has to make (or thinks he has to make) in order to survive the onslaught of the Shadow that pursues him. Maybe there's a second, much easier way to kill that werewolf, but it involves a child, a stone altar, a big bowl, and a knife. Maybe the PCs have more to worry about than just immediate survival, like their reputation in the community, or their immortal souls...
If any of this stuff sounds appealing, I would definitely recommend checking out The God That Crawls, Broodmother Skyfortress, and Deep Carbon Observatory for some fantastic and frightful material in this vein.
*Brennenburg Castle WOULD make for an awesome megadungeon. When I first played the game, it felt like it just kept going down, and down, and DOOOOOOOWN...