I just thought I would share a simple Simple Superheroes adventure I ran with my daughter this weekend. She is 6, so in the spirit of PJMasks or Paw Patrol this is a basic mystery that allows the characters to show off their powers a bit, discover the cause of a problem and solve it without resorting to violence.
My kid is not great at following complex plot, but she knows a lot about biology, so if you are playing with kids you may have to pitch it up or down a bit. We didn't really bounce the dice at all, but this outline could certainly be filled out with more crunch for an older group.
1. Patient Zero.
The players are contacted by Dr. Micron, a "Science Hero" based at a local teaching hospital, meaning he has powers and dresses like a superhero but focuses on exploration type adventures, not crimefighting. Dr. Micron is a brilliant physician who has invented a method to shrink down to the cellular level.
Dr. Micron has a high profile patient: Jose Sevilla, one of the astronauts who participated in the recent first mission to Mars. Sevilla is delerious with fever and has a bad cough, but more worryingly his severly anemic and his skin has turned completely blue. Not frostbite blue: smurf blue. Micron has detected high levels of an unknown organic compound that seems to be toxic.
Dr. Micron suspects that Sevilla picked up and unknown pathogen on Mars. He asks the PCs to help him go into Sevilla's body and find the cause of the illness. If any of them have particularly helpful talents like aquatic abilities, biology knowlege or shrinking powers of their own, he will talk them up.
2. Fantastic Journey.
Micron can shink the PCs down to the size of a single cell using a device that replicates his powers but he will have to spend one strain point for each (he is using his superpower finesse). That should keep him from stealling too much of the show.
He can provide the players with helmets that allow them to breathe inside the body and are equipped with light and radios. One of the eight medical students who follow him around everywhere in the hospital will inject them into the bloodstream.
Grab your phone and bring up a heartbeat sound effect which you should play in the background for as long as they are in there. If tou want to ratchet up the tension give them a set amount of time (1 hour?) before the shrinking process reverses and set a timer.
You're going to want to do a bit of image googling ahead of time so you can show the PCs what it looks like in the bloodstream, what aveloa look like, and so on. Dr. Micron notices that the patient is a bit low on red blood cells. Weird blue crystals are floating around in here that scientific heroes will relaize must be the toxin.
Let them explore the body as they try to find the problem. They can climb up on red blood cells and ride them like inner tubes ttAt some point have them run into some rhinovirus or bacteria that they can beat up (don't want a secondary infection to take hold!). Lymphocytes (white blood cells) can swoop in and clean up if the PCs are having a hard time or the fight gets boring. T-Lymphocytyes shoot antibodies out that make the pathogens stick together while the Phagocytes absorb and "eat" the bound pathogens.
If you want, you can have the immune system recognise the PCs as a threat and force them to fight the white blood cells. Remind them that the more white blood cells they kill the weaker the patient's immune system will become.
3. The Martian pathogen
They can encounter the Martian pathogen whenever the novelty of exploring the body has started to wear out. They call themselves Bloorg-Blorg look a bit like blue ameoba, exept they shed light and acually have eyes and a mouth. The first one they meet will be curious enough to appraoch but will flee at the first sign of hostility. They can speak, although obviously not any human language, and will attempt to establish communication. If any of your PCs have language powers or telepathy this is their time to shine. If all else fails they will resort to sign language and bring the PCs to see a telepathic friend. (Or make them all telepathic if your players are a 6 year old with no patience for this).
The Martian ameobas are actually a microscopic form of intellegent life and have a sophisticated culture. They are running around ripping up red blood cells to get iron which they use as a building material. They have established a city on the surface of the liver. The blue crystals are a byproduct of their metabolism and industry. The Martians will happily take you to their ruling council to discuss the issue.
Talking with the Martians will reveal that they have strong a cultural norm of stewardship... they believe their "worlds" are alive and they work to make it healthier by binding up toxic iron, and producing the blue crystals which collect in the skin and protect their host world from harmful radiation. They had noticed they were in an unfamiliar animal (its so cold for one thing, and tough to get the heat up more than a few degrees) but had no idea they were making it sick and are horrified to learn that is the case.
The relevation that the host body/world is itself intellegent is facinating to them: many philosophers have speculated about this possibility but scientists have never been able to prove it. They cannot confirm or deny the intellegence of multicelluar life on Mars.
They will consent to any plan that has a resonable chance of saving the patients life without costing them their own. In my game it was agreed to surgically remove the city from the patients liver and implant it in a sheep, where they could live without fear of harming a sapient lifeform until they could be returned to Mars. But make your PCs come up with their own solution, and talk it out. If they hurt any of the Martians it will greatly complicate his discussion.
The PC's can exit through the urinary tract, or if they find that too gross, the mouth or nose. Dr. Micron will return them to full size, thank them and arrange for any further procedures that need to be done (unless one of your PCs is a surgeon or something!). There may be a potluck or something to celebrate.
Dr. Micron can be a good contact for the PCs if they need super-medicine or any other "small" favours, but he has no interest in crimefighting so he won't be teaming up on a regular basis.
Once Sevilla has recovered he will be grateful to the PCs and can serve as a contact in the Space Agency in the future. While he didn't encounter animal life on Mars, the PCs have proven its existence so another mission is inevitable.
In the meantime the Martian city should have made it out in one piece and will remain on earth for a while and can serve as an alien setting for future adventures, with the help of Dr. Micron's shrinking process.