Doki-Doki Universe is a "RPG/Simulation/Interactive Story", where you play as a robot searching for his humanity.
In Doki-Doki Universe you visit many differently themed planets all across the universe. They variy from garbage planets, to planets filled with undead monsters or planets rebuilding their society after a meteor catastrophe.
The goal on each planet is to find all the hidden presents, which contain either summon-able creatures/objects or decorations for your home planet, and to solve the problems of and make friends with all the planet's inhabitants.
Getting the inhabitants to like you can be done by performing an action that they like (greeting them in the right way, picking them up, throwing them around) or solving their problems through summoning the objects that you collect. Almost every problem can be solved in different ways and some inhabitants only give up their presents if you make them hate you instead.
The other big part of the game consists of various personality tests that you can undertake. After each test, you are told what your answers suggest about your personality and why the game thinks so and each time you complete enough of the tests, a therapist based on your home planet, adds a few more details to a bigger and more in detail personality profile.
On the Vita actions can be performed with touch controls, on the PS3 they are performed with the right analog stick and on PS4 both options are possible.
You can also send messages, with in-game pictures and animations, to your friends via PSN or Facebook, or look at their personality profiles.
A robot and his friend a balloon get left behind on an asteroid in the middle of space by their family, because the robot is of an outdated model. The robot and the balloon spend years, just hoping that their family will eventually return, when they are discovered by an alien.
The alien is working for a robot recycling corporation, and is tasked with trashing the robot, if he can't proof that he can keep up with newer robot models. The way to proof the robot's worth lies in showing the alien that he can show true humanity.
The robot thus embarks on a quest to show, that humanity isn't solely reserved for humans.