A kid dies of appendicitis. Something feels a little bit off about the death and the funeral. he protagonist becomes friends with a new girl in town and explore Old Town. They find a picture of someone that looks almost exactly like a kid they know - only the picture was a few decades old. Now things are looking really weird.
One day, they find out the truth. The town was the site of an alien invasion. The protagonist and many of his friends are actually an alien strike force. They accidentally destroyed a section of town, and then took over the bodies of the previous residents as their own. The shots help prevent them from rejecting the old bodies. Now it is time to prepare for the downfall of earth. (Through means of misinformation that would be common in today's social media culture.) They will take new shots that help their real bodies come out - bodies that appear superior to human standards. The kids rebel and the invasion is stalled.
The book is short and feels like it jumps to an ending with many loose threads. There are few details about the purpose of their invasion. We know they are somewhat superhuman beings with powerful glove weapons that think they can do a better job of earth. Why earth? How did they manage to become attached to humans? Were they really able to shut it off so easily? There are so many questions. But, you could ignore them and just boil it down to "boy meets girl and saves the world."
Game Changer tries to go super broad, but ends up being too narrow. After a hard hit, a football player notices things are a little odd. It turns out he is now the center of the universe and these hits lead to changes in the universe. Stop signs change colors. His family became rich, but he became a drug dealer. Brown v. Board of Education turned in favor of segregation (because Russian nukes failed), leading to continued segregation and musical stagnation. He finds himself gay and a girl in other cases. The universe goes crazy near the end before he finally ends up with just an injury. If he had the ability to change the course of the universe, why was it so narrow, and why just some of the "hot button" issues of today? And could these little changes really have had such a long lasting impact? Or could unexpected minor changes in the past had a huge impact. There is so much potential for interesting exploration that is squandered in this book.
Unwind came to a fairly satisfying conclusion. This second book builds on it and opens up more threads than it closes. The moral dilemma with "unwinding" people to share their body parts is explored further. We also learn that there was a lot more complexity to the original plan to use "unwinding" as a resolution to the abortion question. There was a development of technology for transplanting of anything. This was initially thought of being something similar to organ transplants of the already deceased. There was also a "youth revolt" due to lack of opportunities. These were tucked aside. 
The kids impacted by the star shards want to use their powers to do good, but they find out that is hard. They try to "undo" harm that they have done and realize patterns to help others. One heals others. He ends up getting followers, including some that harm people so they can get healed. There are episodes where they go into a casino and win a lot of money and then donate it to charity. In the process they remove the glass from a shark tank, yet the water stays. Only at the end do they discover that a traveling companion has been manipulating them to do harm to assist in the harvesting of souls.
A few teenagers live bizarre lives. They seem to have special powers that drive them to do "bad" things. There is also some related special strengths. One teenager draws girls to be romantically attracted to him. Another can see many paths and thus use a small event to drastically change somebody's life. There are abilities to reverse entropy, age in reverse and other mixtures of good and bad. The kids try to get together. They have been fighting their powers, however, one eventually "gives in". They later discover that there are demons from an exploding star that possess them. They find they can "scare" them out by threat of death, but still remain with "good powers". It is an interesting take on super powers that can be both good and bad.
In the future, an alternative to abortion has been found. All babies are born. However, they can be "unwound" as teenagers. When unwound, a person ceases to live as an individual. However, all of their parts are transferred to other people (to help cure problems.) The unwound include wards of state that are not seen as valuable to society. There are also "tithes" from religious people that are willingly offered to be unwound. 
In the future, death is a curable condition. People can live forever. However, this would lead to massive overpopulation. To help control the growth, Scythe's are ordained to take lives. They are above the law and attempt to take people at random. They go through training and apprenticeships and are expected to show caring in their actions. However, as time has progressed, bloodthirsty scythes have entered the ranks. The story tracks two apprentice scythes and their work to uncover the problems in the order. 
I have yet to read any of the novels in the Arc of the Scythe, but I think I have a pretty good understanding of the series after reading these short stories. They are set in the universe of the novel and provide small vignettes of characters and experiences. 
The Schwa was here is a "mostly" realistic story of a kid that is never noticed. However, there are a few "magical" bits that go just enough beyond the natural world. "Schwa" got his last name form a relative who died right as he was saying "Schwartz" to the immigration agent. He is often not noticed by most people. (Though some do have greater ability to notice him.) One boy befriends him. They do a number of experiments to test the strength of "not noticing". They find he can do well at basketball because nobody thinks to guard him. He can do all sorts of other "hidden" tricks. However, they try to sneak in to a grumpy old man and steal a dog dish. This is the undoing, as he gets caught. He and his friends are forced to do service of walking a dog. They also are asked to help the man's blind grand daughter. There is some youthful crushes and hurt fields. We find about the curious case of Schwa being abandoned by his mother in a grocery store cart. Schwa also blows the family fortune on a failed attempt to be noticed. Eventually, he disappears to try to find his mom. There is also a surprising way to get an Italian restaurant chef and a family that struggles with cooking skills. 
Ender's World is made up of a number of essays about Ender's Game. Most are by literary types describing how the novel impacted their lives and writing career. Interspersed with the essays are some short Q&As and other short bits from Card providing details on the book and his writing process.