CODE VEIN takes the user to a post-apocalyptic world with a dystopian environment. The gameplay is presented in the form of role-playing action with freedom of action, battles with fantastic creatures and a vast territory to explore. A catastrophe in the world occurred due to the event “Great Collapse”. The population had to fight monsters that appeared all over the planet.

A group of Revenants, warriors fighting off monsters, was created. Previously, they were human corpses, and then became resurrected soldiers through the implantation of an alien creature. Their heart is modified, and people have received vampire abilities and unique abilities. They will die only if they are wounded in the heart or if it is completely destroyed. Revenants need to drink blood to stay alive. If they don't drink enough fluids, they may lose control, become insane, or become Lost.

The passage begins with the main character awakening in the ruins of Vienna. He learns that society will be decided due to the lack of Blood Beads. If a revenant becomes Lost, it releases a deadly miasma. Because of this, ordinary warriors can quickly become corrupted and fall into madness. Much of the plot revolves around the struggle between the Revenants and the Lost. As the game progresses, the user will also encounter monsters and bosses. The combat system offers gamers the opportunity to parry, use several combinations, special abilities and perform standard attacks with blocks.