Let us start by saying a HUGE thank you for having played our game! We hope you enjoyed playing it as much as we enjoyed putting it together – in spite of the rollercoaster ride we had with this one.

If you are reading these lines it means that you would like to find out a little bit more about the puzzles, story and how they came to be. And boooooy, are you in for a treat this time! We kept notes throughout the whole process!!! Just. For. You! 🙂

However, what comes next is rich in spoilers about the game and story – so if you haven’t fully played the game yet, PLEASE go back and play it first! It will put these next anecdotes in a completely different light!

So go on! Solve the game! We’ll wait for you, promise!

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Done? SOLVED?

Well, here come the spoilers! Hope you enjoy! Hope it won’t be too boring.

We knew what the story of the third game would be, before we were fully done with our second game. Anuj’s long experience with underwater acoustics, and autonomous underwater vehicles (AUVs) — robots that are smart enough to not need human operators — made this one another dream come true, and a sweet stroll down memory lane.

The maritime subject was calling to us! It had to be a submarine – duuuh – so now we just had to come up with the title. We thought if we called the submarine “The Sentinel”, it would be mysterious enough to get players interested. Then came the idea of the Sentinel being stranded somewhere – which pretty much threw us in the direction of “Lost Sentinel” but that was just an overuse of the word Lost – twice in three games. So after a bit of brainstorming we finally had it! The Submerged Sentinel! B-)

Once you know what subject the game will have you can start looking at inspiration. We started by reading a lot of anecdotes, and read as many slang dictionaries as we could (warning: there are some ugly words in there). We really wanted to use a lot of the cool words / expressions we found, but in the end it would have meant adding a lot more content for the players to read, so we just skipped it. The only things that made it into the game, were the interviews with the crew, while solving the Menu puzzle on the first hydrophone. Did you notice the nonsense interviews? Try reading the first letters together from the second half of the interviews. Orsi was entertaining herself a lot while writing them. In the end, those messages seemed so fitting for this story, that we just had to put them there!

The next thing we researched was diving. In spite of the fact that we would both like to try it out one day, and Anuj actually wants to get PADI certification, so far we have never gone deeper than where our snorkels could take us (Anuj points out that this isn’t completely true because he did go diving in a deep-ish tank in an aquarium). So we had a lot of reading to do. Decomp dives, dry suits, breathing air mixes, toxicity levels, cylinder manufacturers – we’ve read everything we could put our hands on! However… None of that made it into the game. In spite of the fact that we had invested weeks’ worth of time into making this math puzzle, after getting feedback from our testers we decided (with heavy hearts) to remove it. But fear not: the puzzle will surely make an appearance in a future maritime adventure 🙂

Just to show you how a puzzle is born. We had the idea of mimicking a “printer failure” on the letter from Mr. Gurges. But in the very beginning, it was only supposed to have just strings of characters in the four corners, with each corner a different color of the CMY color spectrum, which you would then have to merge together using a formula hidden on the page. As you saw, that puzzle idea was further developed, and it’s pretty much the brainchild of Anuj. Somehow he has a magical ability of turning any simple puzzle into hint-exhausting exercise.

The idea of the printer failure developed by stretching it into looking like something random a printer does. The base idea was born while we were doing a print run for The Scattered Cards. Our printed decided, at random, that it didn’t want to print the real text. Instead it started throwing random characters on the edges of the paper. So you see, puzzle ideas can be born anywhere — even when something frustrating happens.

Then we had the idea of hiding something written with a UV pen on the back of the letter. That led to a horrible hunt for small UV lights and how to ship them. It’s honestly a story of its own. Basically Anuj had a couple of sleepless nights and days because of it. All the documentation we had from our shipping company said that they would accept the batteries in those lights, but their agent kept saying they wouldn’t. Then in the end they admitted that it would be ok. While this happened there was a huge discussion about possibilities on the puzzler Facebook group as well, and lots of our players shared ideas. Anuj might even now be know as the Battery Guy or UV Light Guy amongst the puzzler group on Facebook. But hey, what’s important is that everything turned out well in the end.

One suggestion we got from players, and reviewers, is to get rid of unnecessary paper items and move everything non-essential online. We really tried to keep ourselves to that this time. It makes the games lighter, packing much easier and minimizes the resources we need for each game. But at times it is also difficult to just put something online, because we do like the physical aspect of our games. It gives us something non-digital to look at for some time.

Since the beginning we have been trying to reduce our environmental footprint, but this game brought up the issue even more regularly for us. So we thought about it and decided to do a few more things since then. Did you know that our games actually have a negative carbon footprint? Yes, that’s right! Not just carbon neutral, but negative. We plant one tree for each game that we ship! So it’s not just for each order, but for every copy of every game shipped in the past and the future, we plant a tree. We also use carbon neutral shipping, and printing. So in effect, each game you buy is carbon negative, and will be so even when you re-sell it since each tree is good for several copies of our games when it comes to carbon neutral production. You can read a whole lot more about it on our Environment page.

Anuj’s hands-on experience with underwater acoustics made some of these puzzles so much more real! I guess that must also be the reason he managed to make the HydraCON website so believable. It was inspired by some of the prominent research organizations he worked with during his days of being an underwater roboticist and acoustician. By the way, all the articles you see on that website are real. All the information that we placed there is also real. If these kind of things interest you, do read it. We only made up the bits about the map and the hydrophone data (basically the things relevant to the game) – the other things link to real articles, societies, people and data in general. We are hoping that at least a few of you will go down a rabbit hole of interesting learning.

The hunt for the Sentinel, hopping from one hydrophone to the next, could actually have happened. Hydrophones are real – they are anchored to the seabed, and collect data all day long. There is even a global network that is used for communication and research! The manufacturers on the website are real – and Anuj actually got to have first hand experience with some of them! In fact, he still owns four hydrophones of his own from the days of building robots and designing underwater communication systems.

Normally, sound travels much farther in the water than it does above surface. But this means that ambient noise is also a problem. This means that data transmissions in the water can degrade VERY quickly and are PAINFULLY slow (remember dial-up Internet? Well, that was faster and more reliable). The measurement of signal to noise ratio (SNR) is a real thing too. Did you know that besides pressure, the water acidity also plays a crucial role in the changes of SNR? That might not seem to be a “big deal” for data drops from ship and submarines, but underwater animals suffer a great deal because of this. The worst part is that as our climates are changing, our oceans are acidifying. Of course, the primary effects of ecosystem collapse is huge (bleached corals, etc.), but this is making our oceans louder as well. During his research days, Anuj stumbled upon this while researching communication systems and even published a paper on the topic. One interesting thing that was discovered was that whales are actively changing their song due to the increasing noise; the frequency changes measured over the years almost track the changes caused by ocean acidification. Just one more reason to be more vigilant about how we treat our planet.

If you looked at the map, you would have noticed that we have several places on it. The ice shelves, are based on real ices shelves. The only problem is that the Arctic doesn’t have any (anymore), outside of Russia. There used to be some in Canada, but the last one broke apart and collapsed over the last few years. So Matusevich Ice Shelf is a real reference. Ross Ice Shelf is real too, but it is from Antarctica and just happens to be the largest one. All the research station names are real as well, but from the Antarctic, because there aren’t so many of these in the Arctic.

In case you are wondering if Acoustic Dead Zones are a real thing, or if we made them up, well, rest assured they are a very real thing. The fluctuations in salinity, temperature and acidity can lead to such zones being created. They move, and are not permanent, since conditions are fluid. In reality, they also don’t occur at the depths we were dealing with in the game, but that was artistic license. 🙂

The first item we had ready for this game was (obviously?) the map. One other thing we tried to do in this game was to reuse our “pretty” items as many times as possible. This reduces the amount of items we need to fit into each game and hopefully gives our players a chance to enjoy these more than once.

We had a couple of iterations for the map. Originally it was supposed to have marine animals on it, for which, you guessed it, we also did some research.

Did you know that there is only one kind of dolphin in the arctic? Have you ever seen a hooded seal? Would you ever consider free diving with whales? So many questions and opportunities! We wanted to have a puzzle with the whale song, but the game was already longer than our standard ones and I guess we have to leave something for the next maritime game as well.

Designing the map produced one of the most memorable moments for us. We were brainstorming ideas for what animals to put where, and how to depict them on the map. Anuj has a whiteboard in his office, and we were laying these out there. Well, see the picture above. There is a very entertaining looking Dolphin, who got nicknamed the “Reindeer Dolphin” by one of our friends. We love it so much! Watch out for the Reindeer Dolphin to appear in a future game.

Surprisingly, at least for us, the puzzles and 100% of the flow on the map was not ready until very late in game design. We had the base mechanics worked out, and the puzzles as well. But we still weren’t sure of what route would be followed, and how the mechanic would play out. Then as the hydrophones pages were being done, it all started to just fit together. But we felt like we needed one puzzle to lead into the hunt for The Sentinel. This is the very first challenged you encounter from one of the hydrophones: the decryption puzzle (“Confidential”). As weird as this may sound, this first puzzle was the very last one we finished. And this one, is 100% Anuj’s brainchild again (yeah, he owns the blame for all ciphers as a badge of pride). Since he is a programmer, he actually wrote software to help us encrypt the text, however the output still needed to be tested. Which ended up being mostly Orsi’s task (Anuj says that a second pair of eyes is always better).

It was a long evening of testing, which lead to the version of the alphabetic cypher you now have on the Sentinel.fyi website. But by the end of the test, Orsi may or may not have said (with all the love in her heart) that she will skin her dear husband alive. True story or fake news? You’ll never know… (bribes of chocolates may lead to full story being told).

The next nice item we collaborated with an artist for was that cute poster that we, personally, absolutely adore! Our heart breaks a little every time we have to fold one for the game – but we found no realistic way around that. The ship on that poster, however funny the name might sound, is actually a real ship! Anuj came across that name, but it was Orsi who worked it into the “doodle” puzzle, with the cooking frying pan! The real Frying Pan has quite a colored history and it is interesting to read about. When the idea for using the ship named Frying Pan was born, the first idea was very different. Instead of a doodle, we would have had a note that said something like, “The truth is in the frying pan”. But then Orsi made the doodle, and now you know what made it in the game.

If you haven’t guessed it by now, the doodle page was *actually* drawn by Orsi. And the elephant in the final version is pretty much her go-to thing to draw when she doodles during long boooooring meetings. It even got on this paper literally as a doodle – a placeholder for something prettier to come. But then we had a couple of lovely players who tested our early ideas, and they were so entertained by that little elephant, that we decided to keep it in the game.

And this was not the only time we took inspiration from our testers. The hidden websites on the letter from Mr. Gurges (did you find them?) ended up there because D__ solved the initial version too quickly. Also in the puzzle with the multiple clocks? The original one was much MUCH simpler, until R___ went ahead and solved it in under 5 minutes. The chemistry puzzle was also not the way it is now; basically, we gave the first pass to our testers and they blew past it in under 10 mins. We thought it would have been so much harder, and this forced us back to the drawing board. The puzzle initially had a reference to Rutherford, whom we though most no one would know; and to our great surprise all our testers knew of him! Thank you guys! 🙄 You keep us on our toes. But seriously, we love you for it! 🙂

Since we are talking about the puzzle with the clocks; all of those pictures were taken by the two of us! We had a fun day in Cuxhaven, on the beach, for the outside pictures. It was cold, but it was nice to go out to the beach after so long. We actually had a version of this puzzle, where one of the clocks was supposed to show the time in a digital way. In the end, we preferred the version with two clocks together.

Another thank you we have to say is to Ana and Ace from Bluefish Games. We played their game, The Curious Elevator of Mr. Hincks. We absolutely loved one of their puzzles, so much so, that we actually asked them for pointers about how they did it! They were kind enough to let us in on their trade secrets. Play their game if you haven’t already! Then let us know if you figured out which puzzle we are referring to.

What was your opinion about the dive puzzle, in the black sleeve? That was born in a really funny way. We were talking about the story, which in the very beginning had you walking through the submarine. Then we thought, it will be really dark there, so you will need to carry a light with you. How cool would it be if we could mimic some of that? Then, out of the blue Orsi just gave Anuj one of these sleeves to look at and Anuj was absolutely enamored by it! Even now, each time he peers into one of them, to him it feels like he is exploring a hidden world. So the idea of the sleeve was born, and after may iterations, the labyrinth emerged. There was no marine life in the first versions, until Orsi just doodled a few in there. It captured Anuj’s imagination even more so it had to become a part of the puzzle too. Would it surprise you to know, that we even researched what kind of animals live deep down under the arctic? ‘Cos we did 🙂

Another thing we really want to talk about is the story itself. It wasn’t always exactly what it is today. As a matter of fact, we nailed it down just a couple of hours before the first tester started the full test of the game. We had some plot holes in it, which we happily pointed out to each other. Better that way, than a player raising the red flag once the game is done. Why did they go to Palmer station? Why did Haddock do this at all? There was a very short lived idea where he just lost a custody battle and was trying to buy the love of his kid. But we just couldn’t fully believe that scenario. We are both Marvel fans, and we find that the best villains are the kinds that you can connect with. So we added the debt aspect, which would definitely put a decorated navy officer in a bad position that he would desperately want to get out of.

And last but not least, easter eggs! In this game we used two names from the Tintin comics – did you find either of them? There is also a senior officer from Star Trek who makes a strong but friendly appearance as well. He is a very beloved character for both of us, and who knows… Maybe you will get to meet with him again in future games. You’ll just have to stick around to find out!

We had another Enigma Fellowship in-game reference. Did you find it? Actually, more than once. One of the villains from the Sonnburg mafia, who was introduced in The Scattered Cards, makes an appearance in the background. One of our players said that they were not ready to leave the world of Sonnburg behind. Well, R______, it’s still here. Will it make appearances in the future? ▉▉▉▉▉▉▉▉▉▉▉▉▉▉▉▉▉▉▉▉▉▉▉▉▉▉

Thanks for reading through! Send us a message on Facebook, Instagram or just an email to let us know what you thought about the game! We always love to hear from you guys.

Take care, dear Enigma Fellowship member. And stay safe and healthy!