This is the sequel to Analogue: A Hate Story which was a politically charged tale wrapped in the framework of a science fiction visual novel complete with cute Anime companions.
You don't need to have played Analogue to play Hate Plus but I would strongly recommend doing so as it gives you context for what happened to the world the AI came from and in particular really goes into depth about the character Hyun-ae.
Where the first game was Hyun-ae's story, this game is Mute's story. It's just as politically charged, probably even more so, and deals with the biggest mystery from Analogue, which was how a modern society reverted to conservative Neo-Confucianism ideals. If you're not familiar with Asian culture at all the nearest Western equivalent I can think of would probably be The Handmaid's Tale. This game deals with the events that lead up to that big change.
If it sounds serious, it is. And it isn't. It's all told through the personal journals and political council meeting minutes. In particular there several different people whose stories you follow over a series of years and get to see how the subtle and not so subtle changes to their society affect them.
There are also some really fun, light hearted moments with the AI companions including one where you are asked to bake a cake. In real life with a real recipe and then further are encouraged to take a picture of your cake with your companion and send it to the developer to get an achievement. It's all real and I have the achievement to prove it. It was a refreshingly fun meta moment to the game and there are a few others as well like a when the AI cheekily break the fourth wall at rare moments.
There are three main paths which in turn lead to multiple different endings depending on the choices you made. While the texts you read through are the same, the tone and the events that happen with your AI companion(s) are completely different so it really is worth playing through each of the 3 paths at least once.
The game takes place what's supposed to be a small spaceship that you, the space investigator, are on with your AI companion on a 3 day trip back to Earth where you both try to piece together the mystery of the Mugunghwa (the ship that Analogue took place on).
Each path is divided into 3 days where on each day you can only extract a certain number of logs before the ships battery is drained and needs to be recharged requiring you to wait 12 hours. So yes the game does ask you to play the game in installments over the course of 3 days. However there is a way out where once you power down and save you can hover your mouse over that save file, hit the 'S' key and then continue. Note if you do this you cannot get one of the achievements though.
Another alternative is to play day 1 of one path, then day 1 of the other, then day 1 of the 3rd, then 12 hours+ later do day 2 path 1, day 2 path 2 etc. This is what I ended up doing. I think it works well and gives a nice immediate contrast between the differing paths.
One of the changes in Hate Plus is you now get hyper links when people's names are mentioned that gives an image (in realistic art style) of the person with a commentary description from the AI. This made a big difference for me personally as I not only was able to keep track of the names better but also felt like I connected with them more.
Another change is that the AI are reading the logs in Hate Plus for the first time along with you and you get their reactions and commentary that really run the gamut. Even when going back through the documents you already read for the other paths you'll want to scroll through all of it to get the AI reactions because they do differ for each path.
If you do all the paths the game should take somewhere between 9-12 hours, which may vary depending upon how slow/fast of a reader you are, how much time you spend to stop and bake a cake, etc.
Overall I would highly recommend Hate Plus to anyone who enjoyed Analogue, has in interest in visual novels or is just looking for a strongly story oriented game.