Darknut
These black knights have made appearances in several Zelda games over the years. Unlike regular mooks that Link cuts down by the boatload, Darknuts can hold their own. Heavy armor allows then to soak up the hits while their sword and shield fighting style is more guarded than any other opponent. Don't be fooled though these guys can change tactics by throwing their big sword at Link and use a faster and thinner blade to continue the fight. Did I mention it's possible to run into three of these guys at once?
Siam-Siam
Only appearing in Silent Hill: Homecoming, these things look vaguely like pachyderms, but are actually a disturbing fusion of a human male and female. What made a lasting impression on me was the way they move. I got the strange impression that such a combination looked almost plausible. More unnerving is the fact that they react to physical trauma much the same way a real living creature would. Hence, when your character shoots them with a shotgun they stagger and bleed. Shoot them again they collapse like a slain mega-fauna.
Snooper
Getting a game like this to work on the hardware of the day was not easy. The fact that it worked at all is a testament to David Smith's genius. Unfortunately I think he was a bit of a madman too. The game features all sorts of bizarre stuff; 256 "pseudo-degrees" of rotation, a planet buster bomb switch next to (and identical to) the light switch. A smoldering cigarette that kills you as soon as you pick it up, a jail cell with potentially lethal electrified floor plates, fatal vertical shafts in the ships reactor room that have no safety railings, and that's just the tutorial area!
Enemies consist of googly-eyed geometric shapes that attack the player on sight but flee if they are backed into. They come in different types too; warriors, scouts, workers, queens and so on. The worst of these is the "Snooper", a kind of invincible ground crawling critter that appears if the game is played for more than two hours in a 24 hour period. Even if the player takes a break it will continue to appear again and again at ever shorter intervals. It stalks the Star Marshall and drains a large amount of life if it manages to catch him. Sound bad? Here's where it gets truly insidious...rather than trying to explain I'll just quote from David Smith's memoirs regarding the game:
The system would ultimately crash even if you just stood in one place and didn’t do anything at all. This made me realize that it probably wasn’t something that the game player was doing, but perhaps one of the autonomous creatures that inhabited the world. Finally, I created a real-time map of the world where I could track the movement of the creatures. What was supposed to happen was that the creatures would wander around the world, pretty much at random. When they hit a wall, they would simply turn in another direction. The same thing would happen if they hit another creature… except one of the creatures was special. There was a slow-moving slug like creature that knew how to follow the game player’s trail. When it came across another creature, rather than bouncing off and risk losing the trail, I made it so that it would destroy the other creature and stay on target to find you. This worked great, except that on some rare occasions, this slug could do to a wall what it did to the other creatures. That is, it could delete it. This meant that the virtual door was now open for this creature to explore the rest of the RAM on the Macintosh, deleting and modifying it as it went along. Of course, it was just a matter of time before it found some juicy code. In other words, the bug was a REAL bug.
You might be wondering why this game wasn't more popular. Well, it basically boils down to the game very easily ending up unbeatable. This was intentional design in many cases. A pair of inescapable 2001 A Space Odyssey tribute rooms being one example. Ostensibly the player was supposed get his ship repaired, rescue six cryogenically frozen children (colony survivors that the aliens missed) via power loader and teleportation pods, then blast off and hit the aliens with an implosion weapon (remember they absorb energy!). Needless to say doing all that is incredibly hard. So much so it makes completing Dark Souls look like a piece of cake by comparison. Regardless, the Snooper will stay in my mind...deleting...modifiying...now that is a foe of merit!