I. Theme

Single-player popular science adventurous game. We meticulously designed several levels, covering most of the digestion process in human body, enabling the players to embrace joy and popular science at the same time.

II. Overview

The game can be divided into eight levels, containing oral cavity, throat, esophagus, stomach, small intestine, large intestine and the anus, matching level one to eight respectively.

III.Levels

Prologue:

Dear warrior, welcome to the human digestive tract! This is going to be a wonderful adventure, and I am your guide. Curious about who I am? You will figure it out on after. During this journey, you will pass through the mouth, the tract linking between, stomach, duodenum, Jejunum and ileum, ascending colon, descending colon, sigmoid colon a total of eight levels, in turn. Eager for the experience of feeling digested? Come on and give it a try!

Level 1: Jack for Enzyme

Foreword:

Dear warrior, here is the mouth, your very first stop on your journey. If you wish to be more completely digested and absorbed afterwards, then you must be thoroughly chewed. You need to be ground by teeth and preliminarily broken down by salivary amylase so that you can be fully utilized in the subsequent steps.

Guide:

You need to jump in the mouth and hit the teeth. At this point, salivary amylase will be produced, which runs randomly in the mouth and you need to combine with it (collide with it). There are 7 teeth, and you need to jack them up in turn and come to the end - the epiglottis cartilage - and that’s a success.

Controls:

Press ← and → to control the left and right movement, press SPACE to jump up, and touch the end icon to finish the game. When the game finishes, press SPACE to exit, press ENTER to move on to the next level or restart.

Science Link:

Salivary amylase:

I am a type of hydrolase secreted in the mouth by three pairs of salivary glands (mandibular, parotid and sublingual) and many small mucus glands in the oral wall. Don’t neglect me because of my small size, I can hydrolyze numerous soluble starch, straight chain starch, glycogen and other substances, as well as the first part of the guardian of the digestive system!

Epiglottis:

I am behind the back of the tongue, like a cute small leaf, wide at the top and narrow at the bottom. I am just like a flexible and intelligent switch, that automatically turn on when breathing and speaking. But when there comes food, I would cover up the laryngeal cavity to prevent food from entering the trachea. So guys, just try not to talk when eating, or I may be too busy to adjust, causing you to be choked.

Level 2: Esophagus Adventure

Foreword:

Dear warrior, you have left the mouth and reached the second chapter - the esophagus. In this long smooth tube, you need to pay attention to avoid barriers while trying to collect coins to reach the junction of the esophagus and the stomach - called the cardia.

Guide:

Players control the character on the smooth surface of the esophagus and try to avoid stomach acid reflux, food debris and other obstacles. Collect gold coins to speed up. Surviving for 1 minute and keeping the score greater than 0 to reach the cardia, and enter the next chapter.

Controls:

Use WASD or ↑↓←→ keys to control movement, and press the pause button on the top right corner of the screen to pause. After this level ended, click the option on the screen to choose to enter the next level or exit.

Science Link:

Throat:

I am the part of the cavity after the oral and nasal cavities and above the esophagus, which is the shared passage for eating and breathing, as well as the linking the mouth and the esophagus. So indeed, I am really a very important traffic channel, made up of muscles and mucous membranes. However, perhaps just because I'm too tiny, people only think of me when they got their throat hurt. But as long as humans take good care of themselves and don't get cold, I won't get inflammation.

Esophagus:

I'm very strong because I'm a channel made of muscle that connects the throat to the stomach. Haha, but actually I cannot digest anything at all by myself, I just help transport food into the stomach, and my brothers behind me will digest and absorb the food finely and thoroughly.

Level 3: Swim through Stomach

Foreword:

Dear Warrior, congratulations on passing the throat! Now, welcome to the world of the stomach! Here, there are two main types of digestion that food goes through: one is mechanical digestion accomplished by the muscle stretching and bending activity of the digestive tract, which grinds the food and mixes it thoroughly with the digestive juices, then delivers it continuously to the further part of the gastrointestinal tract; the other type of digestion is conducted by the secretion of digestive juices by the digestive glands.

Take a closer look, you are now swimming in "stomach acid". The human stomach is secreting gastric acid whenever, and its secretion activity tends to peak a few hours after going to sleep and lowest in the morning before waking up. When food enters the stomach, stomach acid secretion will begin to increase! Do you notice the enzyme swimming in the stomach? That is called pepsin. The pepsinogen in the stomach must first be activated by stomach acid before it can be converted into pepsin, which catalyzes the digestion and breakdown of proteins. Apart from that, you will be exploring the mysteries of the intestinal tract in the future, so I might as well tell you secretly in advance that the carboxypeptidase in the intestinal pancreatic fluid protein digestion system converting into carboxypeptidase that can catalyze protein breakdown, still require the pepsin to be activated! Therefore, if the gastric acid secretion is insufficient, pepsin cannot be produced, which will not only affect the digestion of protein in the stomach, but also affect the further digestion of protein in the intestine and the absorption and utilization of amino acids. So, dear warriors, for the sake of a brighter path ahead, fuel your spirits and start your journey in hydrochloric acid!

Guide:

The HP is displayed in the upper right corner of the screen. When diving in hydrochloric acid, you need to dodge randomly dropped food and dodge slime enzymes thrown by H. pylori. When encountering pepsin in the hydrochloric acid, you need to get closer to it and bind with it (i.e. collect it). The task is to destroy all the Helicobacter coming to attack and bind with a sufficient amount (6) of pepsin to enter the pylorus before your blood level declines to zero.

Controls:

Press ← and → to control the left and right movement, press SPACE to shoot at H.pylori, press p to pause, and press z to continue. After this level ends, press SPACE to exit, press ENTER to enter the next level or restart.

Science Link:

Pylorus:

It is the part of the stomach that connects to the duodenum. It not only has the function of linking, but also secretes mucous proteins through the glands in the surrounding circular muscle, which can protect the gastric mucosa from abrasion by rough food and erosion by stomach acid.

Helicobacter pylori:

I am the only bacteria found in the stomach that can survive! Not only can I protect myself from stomach acid by hiding in the mucus layer of the stomach wall, but I can also secrete urease, mucolytic enzymes, phospholipases and other toxic enzyme weapons! Watch, my urease can convert its urea produced by metabolism into ammonia to neutralize stomach acid, while mucinase and phospholipase can catalyze the decomposition of mucus and phospholipids in the stomach, respectively, and provide me with sufficient food supply. Believe it or not, the ammonia produced by urease may also cause the energy metabolic disorder of stomach cell, plus, phospholipase can directly sabotage the human body's gastric mucosal protection. Infecting a human to get gastritis or even gastric cancer is just a thing without sweat for me. What are you waiting for? Are you scared? I bet you dare not come.

Level 4: Catch-it!

Foreword:

Congratulations, dear warrior, on successfully escaping the attack from H. pylori! By the way, although H. pylori look scary, it is actually not difficult to prevent. In daily life, good habits to keep clean(such as washing hands before having a meal after the toilet, regular sterilization of dishes) and meal portioning can effectively reduce the chance of H. pylori infection!

Guide:

The character keeps running forward in the duodenum while going to catch as much bile and pancreatic juice as possible with the container - failure to capture will have a negative effect on the HP. The falling mixture contains bombs - stomach acid, Helicobacter pylori, parasites, fungi, mold - one touch will lose (game over) and needs to be dodged.

Controls:

Press ← and → to control left and right movement, press SPACE plus ← and → to double the speed. And you can press p to pause, and press z to continue. After this level finishes, press SPACE to exit, press ENTER to enter the next level or restart.

Science Link:

Self-introduction of the duodenum:

I am the duodenum, shaped like the letter "C", because I am about the length of twelve fingers in width, so I am called a "duodenum"(duod stands for 12 ). I have a part with a ball-like shape, a descending part, a horizontal part and an ascending part. Stomach and I are good friends, and we accompany each other all the time. He is very kind to me and often shares with me good food - acidic surimi. But actually...I don't like acidic cereal, I'd be hurt by the stomach acid! But the pancreas, liver and gall bladder will send me pancreatic juice and bile, which not only neutralize the acid in the chyme, but also help the further digestion of the chyme! And I'm going to further break down it into small pieces to share with my friend after me, the jejunum!

Acidic chyme:

The food gift from the stomach, the initial breakdown by stomach acid and is ground up and present like porridge, is acidic because it is mixed with stomach acid. If it is not neutralized it can cause damage to the lining of the digestive tract that follows.

Secretin and cholecystokinin:

When the pylorus opens to release chyme from the stomach to the duodenum, the acids and fats in the chyme stimulate the lining of the duodenum, and the epithelial cells of the duodenum would release secretin and cholecystokinin, which further promote the release of bile from the liver and gallbladder.

Bile:

Bile is secreted by hepatocytes, and during the non-digestive period, bile is transferred to the gallbladder for storage via the hepatic duct; during the digestive period, bile can be discharged in large quantities directly from the liver and gallbladder to the duodenum, promoting the digestion and decomposition of fats and the absorption of fat-soluble vitamins. At the same time, bile can neutralize the gastric acid in acidic chyme and avoid causing damage to the duodenal lining.

Pancreatic juice:

The exocrine part of the pancreas secretes pancreatic juice to the duodenum according to the demand of digestion, and the bicarbonate in it also helps neutralize stomach acid. Meanwhile, a variety of digestive enzymes in it help further break down large molecules in food - pancreatic amylase breaks down starch into maltose, pancreatic maltase breaks down maltose into glucose, and pancreatic lipase breaks down neutral fat into glycerol and fatty acids.

Stomach acid:

After the initial processing of food, stomach acids and food form acidic chyme, which then enters the duodenum. When the mucosa of the duodenal lining is damaged, stomach acid will hurt the duodenum causing ulcers.

Parasite, fungi and mold:

Unclean food eaten by humans can negatively affect the intestinal flora and intestinal lining, resulting in intestinal discomfort or disease.

Level 5: Interesting Intestine

Foreword:

Dear Warrior, congratulations on your successful breakthrough from the duodenum! So far, your acidity has been neutralized! You are being further digested! The nutrition - folic acid, iron and vitamin D3, fat and protein - have been fully absorbed! Especially the iron element! Next, look at the small intestinal villi at your feet - now you're in the territory of the jejunum and ileum! Although the mammalian small intestine after the duodenum can be further divided into an anterior jejunum and a posterior ileum, there is no clear boundary between the two. The inner surface of the wall of the jejunum and ileum has a large number of circular folds, on which there are many villi-like protrusions, called small intestinal villi, which can play a role in increasing the absorption area of the small intestine and filtering substances.

Guide:

Single line track, jump to avoid the harmful bacteria walking around, colliding with them will lose HP. Collect a sufficient amount of gold coins (30 points) and reach the appendix colon mouth to win.

Controls:

Press ← and → to control left and right movement, and press SPACE to jump up and reach the end icon to end the game. When jumping up and squashing the harmful bacteria, you destroy the harmful bacteria; but if you touch the harmful bacteria in other ways, you will lose HP. After this level ends, press SPACE to exit, press ENTER to enter the next level or restart.

Science Link:

Pathogenic Bacteria Collection:

Staphylococcus aureus, S. aureus:

To tell you the truth, my habitat is not constrained to the intestines only! I love to live my happy life in the skin, nasal cavity, intestines, and dirty wounds of humans and animals, and I can also make my way into the air and contaminated water. I prefer to hide in food (especially leftovers!), meat, eggs, milk and related products, pastries ...... I love just exactly what humans like to eat! The enterotoxins I produce can cause food poisoning, nausea, extreme vomiting, abdominal pain, diarrhea and other symptoms of acute gastroenteritis, not only has a short course of illness, but also a strong effect when attacking, it would frighten your soul out of your own body! Ahahahahahahahahahaha ......

P.Aeruginosa:

Humans also call me Pseudomonas aeruginosa, and just like my buddy Staphylococcus, I’m not simply living in this little land of intestines! Damp places are my favorite! I’m not only one of the most common bacteria existing in soil, but also I can survive in water, air, human skin, respiratory tract and intestines! People say that I'm a real bully, and I love to mess up in hospitals and infect patients' post-operative wounds - but I don't really care about what they say though, since the weakened or immune- compromised inpatients get infected by me, they're in big trouble!

P.mirabikis:

Well, to come honest, I am actually(at least sometimes) a part of the normal intestinal flora, and people call me conditionally pathogenic bacteria: under normal circumstances, I can do no harm to people, but when the human intestinal tract function suffered disorder or the body's resistance ability declined, my presence may not only bring the symptoms of food poisoning, but also may cost humans their lives! Telling you a secret, I like to hide in food produced by animals, especially meat ...... The little thing, which kind of food are you from, why not tell me about it...

Level 6: Float Float Float

Foreword:

Dear warrior, you have just passed successfully through the ileocecal - the dividing line between the small and large intestines! You have skipped the cecum and appendix and made it from the ileocecal to the ascending colon. Go and start your journey to the large intestine now! In this chapter, you will go up at an even speed and encounter harmful bacteria, so remember to escape from them! Good luck!

Guide:

After entering the ascending colon, you are pushed by the beneficial bacteria at an even speed upward, during which you may encounter many small clouds composed of harmful bacteria hand in hand, the player can use the ← and → buttons to control the left and right movement of the character so as to duck these harmful bacteria, one touch of harmful bacteria leads to failure. At the same time, you also have to prevent falling from the beneficial bacteria. When you rise to the top of the ascending colon (when the height reaches 500), you win.

Controls:

Press ← and → buttons to control left and right movement. Press p to pause, and press z to continue. When this level completes, press SPACE to exit and press ENTER to enter the next level or restart. (Bonus: press 'u' 'c' 'a' 's' at the same time to revive)

Science Link:

Salmonella:

A common food-borne pathogenic bacteria, most of them can only cause diseases in animals such as livestock, murine species and poultry, but sometimes they can also contaminate human food and result in food poisoning. According to relevant statistics, among all types of bacterial food poisoning in countries around the world, food poisoning caused by Salmonella often tops the list.

Clostridium botulinum:

Mainly exists in soil, human and animal intestines and decaying matters. Only a few of them are pathogenic, and normally, all pathogenic ones can produce exotoxin and invasive enzymes. Clostridium botulinum can produce botulinum toxin when it proliferates in food, and when people consume food containing the toxin, toxin-based food poisoning can occur.

Bacteroides fragilis:

Most strains are normal intestinal parasitic bacteria. Among them, Bacteroides fragilis, is mainly present in the intestine and is 100 to 1000 times more abundant than E. coli in the intestine. In clinical specimens, it is a common bacterium in appendicitis and sepsis.

Escherichia coli:

E.coli is a conditionally pathogenic bacterium that can, under certain conditions, cause gastrointestinal infections or infections of various local tissues and organs, such as the urinary tract, in humans and many animals - mainly caused by infections with specific bacterial hair antigens, pathogenic toxins, etc.

Veillonella:

Strictly anaerobic, parasitic in the oral, intestinal and respiratory tracts of humans and animals. Produces endotoxins and therefore plays a role in various mixed infections.

Level 7: Descending Colon Slide

Foreword:

Dear warriors, congratulations on your successful breakthrough to the colon! Some of the nutrients were digested and absorbed! Next, you will skip the lateral transverse colon and directly enter the descending colon, where you will have more adventures, good luck!

Guide:

The background is the longitudinal section of the intestinal tube, and the left and right sides are each made of intestinal walls as walls with various cells and bacteria as interactive elements. You need to control the character to jump between the left and right walls to avoid the attacks and increase the score. When your score reaches 1000, it will stop spawning new walls and interactive elements and show that you have arrived at the destination.

Here’s the chart considering the effect of each bacteria in the game.

Name	Effect
Bacteroidea fragilis	Minus 50 points if there’s debuff, otherwise add 50 points.
Clostridium tetanus	5% chance of mortality, 35% chance of minus 50 points.
Tetanus immunoglobulin (Only appears when damaged by Clostridium tetanus)	Add 50 points.
Clostridium sepsis	10% chance of mortality, 40% chance of minus 50 points.
Bifidobacterium bifidum	Add 50 points upon one hit. Continuous 3 hits adds 150 points in total, and receive rage mode for 10s.
Lactobacillus acidophilus	Add 80 points upon hit. Continuous 3 hits adds 200 points in total, and receive rage mode for 15s.

Controls:

Use WASD or ↑↓←→ keys to control movement, press p to pause, and press z to continue. After this level completes, click the options button on the screen to choose to exit or enter the next level of the game.

Science Link:

Bacteroidea fragilis:

It can help digest a variety of substances, but can cause infection after trauma or under pathologic conditions, and death when severe.

Clostridium tetanus:

Generally not pathogenic in the intestine, but can enter body fluids through wounds and cause tetanus, resulting in severe muscle spasms and a lethality rate of about 10%.

Tetanus immunoglobulin:

It specifically neutralizes tetanus toxoid, functions as an antidote, and is generally used in patients with high-risk wounds who have not been vaccinated against tetanus.

Clostridium sepsis:

Generally not pathogenic in the intestine, but can lead to fatal infections induced by immune deficiencies and malign tumors, with a mortality rate of about 79%.

Bifidobacterium bifidum:

Essential bacteria in the human intestine, play a significant role in maintaining intestinal homeostasis, activating the immune system, and inhibiting cancer.

Lactobacillus acidophilus:

Antagonize many pathogenic bacteria and help cholesterol excretion, and is used in the production of many fermented dairy products.

Level 8: Maze&Quiz

Foreword:

Dear warrior, finally, you have arrived at the last chapter of your intestinal journey! This is the labyrinthine sigmoid colon, and I am the anal sphincter, and I guard the end of the digestive tract. All the food that has been digested needs to leave the body from here through me, and you are no exception. You need to get out of this maze and answer my questions with what you've learned along the way, score higher than 75, and I'll let you go. The test starts now!

Guide:

First, you need to pass through a small maze, and it’ll enter the answer screen after coming to the exit. There are 20 popular science questions. After entering the answer screen, you need to answer at least 15 questions correctly before being considered a success. Among them, each question will show the answer after you answer, and stay on the screen for about two seconds, you can see what the correct answer is.

Controls:

Use the ↑↓←→ keys to control movement, and click on the answer you choose on the screen. After this level ends, press SPACE to exit, and press ENTER to restart the game. After completing the entire game, you can push ENTER to view all the bonuses you may miss. We suggest you press only one key at a time.

Science Link:

Fibrobacterium phagocytophilum:

Hydrolyze many macromolecules, such as chitin, pectin, starch, agar and cellulose.

Ackermannella myxophilus:

Feeding on intestinal mucosal proteins, it is believed to have the property of anti-inflammatory, anti-obesity and type II diabetes prevention.

Lactobacillus rhamnosus:

Secrete substances which can regulate apoptosis and lives of intestinal epithelial cells, contributing to intestinal anti-inflammation and environmental homeostasis.

Clostridium difficile:

Produces enterotoxins, cytotoxins, etc. Resulting in diarrhea and inflammation in infected patients. Fecal-oral transmission. Washing hands before meals can prevent infection.

Salmonella enterica:

Present in untreated ingredients that can cause intestinal infections. Employing pasteurization, irradiation sterilization and cooking thoroughly can effectively eliminate and prevent Salmonella Enterica infection.

Listeria monocytogenes:

Present in unpasteurized or spoiled dairy and meat products which can cause fever, gastroenteritis, sepsis, meningitis, etc. Thorough washing and high-temperature cooking of food to prevent infection.