Some anime have only one season and that is too much. Others have over a thousand episodes and it still isn’t enough. But a few rare anime ended before fans got enough of them. Death Parade is a perfect example. In 2015 twelve episodes were aired in a single season and it's simply not enough. So many questions were left unanswered, so many characters left unexplored, and so many consequences hadn’t been explored. There is certainly something to be said for ending on a high note rather than stretching something further than it can go just to create content, but there was still so much further Death Parade could have gone.
Death Parade stars Decim and his unnamed assistant as they wait in the afterlife for souls to come to their bar. The souls are then forced to play various games with their lives on the line. Throughout the games, the darkness in their hearts is revealed and Decim as arbiter decides their eternal fate. Either they are sent for reincarnation, or they are sent to the void. Viewers slowly come to realize that his assistant is also there for judgment due to the machinations of other more powerful beings with reasons unknown.
Short Overview
Every single episode introduces at least two human characters who need their lives judged. They serve as plot pieces and not really the story themselves, although their contained situations are certainly interesting and impactful. The real overarching story comes from Nona, and Oculus, with Decim and the humans serving as mere pawns.
Oculus appears to be something of a god figure, although not god, whereas Nona is in charge of the arbiters and likely an arbiter herself. She has grown tired of the way things are done and seeks to break the four rules of arbiters to give what they do meaning. In doing so she uses the black-haired girl to try to give human emotions to Decim, which ultimately succeeds despite Oculus’ desires against it.
Unanswered Questions 
The first two episodes raised one very important question that was never really addressed. Decim makes a mistake, both Nona and his assistant make it clear that he sent the wrong person to the void and to reincarnation. This raises two questions. First, was anything done to right the wrong done to Machiko? Secondly what is done to prevent these errors in the future? Decim certainly faces no consequences aside from a mild scolding.
Nona herself raises some interesting questions; her eyes imply that she is an arbiter, but she describes herself as a manager. Also one of the rules of an arbiter is that they can never stop judging, because that is what they are, and yet she does not judge. What is Nona? What makes her different than an arbiter?
More broadly what are any of these beings? Oculus near the end states that they are all dummies and asks if Nona has figured it out yet. But it is never made clear what exactly she was supposed to figure out. It is hinted that it has something to do with the void, but audiences are left to guess for themselves.
What happened to Decim? He was obviously able to unlock human emotions, which not only implies that all arbiters could be emotional, but also implies that something dramatic has changed within him. What will the implications of this be? Can he continue judging? Is he a better or worse judge for it? There are just so many implications to something like this that were never explored.
Quin, another arbiter who was never really explored also leaves much to the imagination. She is clearly working with Nona to get Decim emotions, and she gave up being an arbiter. What is her deal? Why is she different than Ginto or one of the other (presumably) 88 arbiters in this tower?
Questions Never Answered About the World
It is briefly mentioned that Nona is the manager of “this” tower, which implies that there are other towers as well. There are so many possibilities there that could be explored: do they all do the same thing, does Oculus oversee them all, and so much more. Another briefly introduced character, Castra, is fascinating, but she introduces the idea that humans are dying too quickly. This is never explored, the audience doesn’t know why this is a problem, nor what is being done about it.
There is so much more depth to this vibrant world than audiences were treated to in this first season. Another season exploring more of the world and the ramifications of Nona’s actions would be fascinating. Even if the assistant was never recovered from her judgment, just watching the rest of the characters deal with the fallout and exploring this alternate world of dummies would be well worth the time. Of course, seeing the life stories of more people would be desirable as well.