Hate Plus continues right after the ending of Analogue: A Hate Story: The player sits with one of the two AIs in a small space ship to Earth and the journey will take three more days. Fortunately the AI found a way to pass the time: a bunch of previously undiscovered log files. While reading them, the player will learn more how the society on Mugunghwa moved towards "year 0" when the patriarchy dynasty discovered in the first game was started.
The majority of the game is spent with reading these files which are divided into six thematic blocks. The player can also search for key words (title or author) or use the character reference list with (in some cases) a portrait and a short summary what was learned about him/her. The player can choose up to six files at the time to retrieve, but each drains a bit of ship power. After reading those - as long as there is power left - more can be chosen. When the all power is up, the player can still read in the files, but needs to go to bed and wait for the next day in order to continue the game. This is associated with a twelve-hour waiting period in real life. Another important part is interaction with the AI: it not only makes short comments when reading through a file, but also asks for communication at certain times, e.g. after reading a certain file or starting a new day. During those interactions, the player sometimes has to choose between three answers (mostly yes/no/maybe) which influences the relationship to the AI - but she may be not afraid to call the player (not the player character, but the actual player) out when she catches an obvious lie.
If the player travels with *Hyun-ae and *Mute as well their relationship (resentful, friendly or in love) is determined by importing a save game or by answering a few questions when starting a new game.
Hate Plus has an intentionally unobtainable Steam achievement called "Level Four Revive Materia", a reference to a famous rumor about reviving Aerith in Final Fantasy VII. Like its namesake, the achievement focuses on averting the death of a major character, which is completely impossible.