Hello Backers,

It’s been a wild ride, but the This and That campaign is nearly over, with less than a day to go!

I’ve had a couple of people ask about getting This and That for two systems, instead of one or three, so I’ve created an add-on option for extra copies so you can get as many as you want.

Speaking of add-ons, if you are thinking about adding one, now is the best time. They’ll still be available in the pledge-manager, but those won’t count for stretch goals, and it looks possible that add-ons might might make the difference between hitting a stretch goal and not.

For our final preview, the voters asked for traps. Not every chapter in This and That includes traps, but those that do I had a lot of fun with.

Below is the hourglass room trap. I enjoy this one because it’s not the sort of trap that is a one of “gotcha,” but the sort of trap that you can build a whole encounter around.

Hourglass Room

Mechanical Trap

This room appears to have a floor covered with sand. Characters who make a DC 15 Wisdom (Perception) check notice that the sand has a strange pattern to it. A DC 15 Intelligence (Investigation) check can deduce the presence of vibration sensors beneath the sand.

These vibration sensors detect anybody walking on the sand. Three rounds after any character enters the room, the doors slam shut, and sand begins to drain from the center of the chamber. 

The doors have no keyholes, but characters can attempt to release the latch holding it in place with a DC 25 Dexterity (thieves' tool) check or break it down with a DC 25 Strength check.

While active, the sand in the room is difficult terrain. On initiative count 0, each creature standing on the sand must make a DC 15 Strength saving throw or be pulled 10 feet toward the center of the room and become restrained as they sink into the sand. They can free themselves as an action by making a DC 15 Strength (Athletics) or Dexterity (Acrobatics) check. Characters already in the center of the room when they fail their Strength saving throw instead fall through a five-foot opening and drop into an identical room below, suffering 7 (2d6) bludgeoning damage in the process.

The room below is identical in all aspects, though upside down, and it is rapidly filling with sand as from the upper level. Traveling up through the hole is only possible with flight, levitation, or similar abilities, and even then, requires a DC 15 Strength (Athletics) or Dexterity (Acrobatics) to get past the falling sand.

On the fifth round at initiative count zero, all the sand drains from the top room to the bottom. The entire two room complex flips. Each creature in either room must make a DC 15 Dexterity saving throw, taking 2d6 bludgeoning damage and falling prone if they fail or half that and remaining standing if they succeed. The top room becomes the bottom, and the bottom becomes the top, and the sand starts draining again. This repeats every five rounds as long as the vibration sensors sense movement in the sand.

Heroes can avoid these sensors if none of them are touching the sand. They can also try to hold remarkably still to trick the trap. If holding still each creature in the room cannot move or take actions and must make a DC 15 group Dexterity (Stealth) check. If at least half succeed, they hold still enough to trick the sensors. Characters can also disable the vibration sensors. Each room holds three sensors, and characters must find and disable the three. While there are three sensors in each room, only the ones of the room currently on top matter. While in the top room, characters must first find the sensors buried under the sand with a DC 15 Intelligence (Investigation) check and then disable them with a DC 15 Dexterity (thieves' tools) check. The sensors in the bottom room are easier to spot, but hard to reach because they are on the ceiling. Characters can reach them with a DC 15 Strength (Athletics) check, at which point they can disable them.

 However the heroes deal with the sensors, once dealt with, the top room drains of sand until it flips one final time when the outer doors open and the shutter connecting the upper and lower rooms closes.

That’s all for now. I’ll plan to do another post tomorrow after the campaign end.

-Matthew

Hello again This and That backers,

We are starting to round the corner into the home stretch, with just a week left on the campaign. We continue making steady pace towards stretch goals, and I think we have a really good chance of hitting one when the end of campaign rush hits.

Thanks to everybody who voted in our last preview poll. Real-world history was the clear winner. We have one more poll up for our final preview next week.

Real world history is always one of my favorite parts of writing these. It’s interesting to see how these simple technologies evolve (or sometimes stay the same for centuries). Plus it’s fun to see many tropes common in fantasy RPGs do or don’t line up with medieval history. 

One of favorite things to see is a back and forth, where technologies respond to developments elsewhere. This is what happened with cryptography, as new cyphers emerged after people cracked the old ones. 

Keeping secrets stretches back to the start of human history, but formal ways of communicating them—codes, cyphers, and steganography—are more recent inventions.

One of the first examples we know of are clay tablets from around 1500 BCE that show an encoded recipe for pottery glaze, the ancient world's trade secrets. Hebrew scholars have used substitution cyphers since at least 500 BCE.

While mercantile and religious secrets were important, the most common reason for passing hidden information is war. In his Histories, written around 440 BCE, Herodotus describes hiding a message about an upcoming attack on the wood backing underneath a reusable wax tablet. At some point in the 300s BCE, Aeneas Tacticus gave an even more thorough description of ways to send hidden messages in his text How to Survive a Siege. Many of those techniques, like invisible ink and marking letters in otherwise innocuous texts, continue to be used in modern times.

The Caesar Shift
Substitution cyphers, replacing one letter of the alphabet with another, existed long before Julius Caesar. However, having once been emperor of most of the western world, his name became associated with this fundamental form of cryptography. In the Caesar shift you substitute one letter for another, always a set number of letters away from the original, just like popular decoder rings. It's said that Julius Caesar personally used a shift of three for his communications, so A became D, B became E and so forth.

Simple substitution cyphers like these remained common up through the Middle Ages, but these codes could all be easily broken, thanks to the code breaker's most powerful weapon . . .

The Frequency Table
Frequency tables record how common each letter is in standard written communications for a given language. In English, E is the most common letter, so when looking at a simple substitution cypher, the most common character is likely to be E.

Al-Kindi, an Arabian mathematician, created the first frequency tables in his aptly named Manuscript on Deciphering Cryptographic Messages. For centuries these techniques were known only to the Arabic-speaking world, but the ideas moved to Europe by the time that continent had its Renaissance. 

In response, cryptographers developed ways to thwart analysis, such as translating common letters to more than one symbol in the code and switching what symbols mean as the message proceeds, so the first letter might be encoded by the letter three steps away, but the next might be four steps, and then five steps. Though these codes were harder to break, none were impossible to crack, and the additional steps took more time and increased the error rates for the people sending and receiving the messages.

Keys and Automation
The invention of the cypher key finally defeated the frequency table. Keys are simply algorithms used to encode information that include strings of randomly generated text. One of the first examples is the one-time pad, first described in 1882 and rediscovered and patented in 1917. These pads were simply papers with random letters that were used to determine what sort of Caesar shift to apply. With the advent of electronic cypher machines and later computers, these keys became ever increasingly complex.

Though the key became cryptographers’ greatest strength, it also became the main focus of attack, because if the decryptor could get their hands on the key, they could freely decode messages. Indeed, some of the first breakthroughs decoding the Enigma machine, used by German forces in World War Two came because lazy enigma machine operators set the key to settings like AAA or BBB.

Modern cryptography relies on long keys and computer algorithms to encrypt and decrypt data. The process has become so easily automated that it's used not only for trade secrets and military movements, but also everyday emails. While far more secure than codes of the past, the ever-increasing speed of computers also increases the ability to crack codes. Computers can use “brute force” to try every single possible key for codes that were “unbreakable” decades ago. Despite all that computing power, just as with the Enigma codes, humans are by far the weakest link in modern cryptography. It's far easier to trick a person into revealing their password than to decode their information on their hard drive.