Katana Zero is a 2019 platform game created by indie developer Justin Stander. Set in the dystopian neo-noir metropolis of New Mecca, it follows Subject Zero, a katana-wielding assassin with amnesia who can slow down time and predict the future; Zero must unravel his past while completing assassination contracts. Katana Zero features side-scrolling hack-and-slash gameplay in which the player attempts to kill all enemies in a level without being hit. The player uses Zero’s abilities to manipulate time, dodge attacks, and take advantage of environmental hazards. Outside the main gameplay, the player converses with non-player characters through dialogue trees.
Katana Zero is a 2D platform and hack-and-slash game presented from a side-scrolling perspective. Controlling the player character, the katana-wielding assassin Subject Zero, the single player completes assassination contracts given to Zero by his psychiatrist. Zero can run, jump, wall kick, pick up and throw items, attack using his katana, and dodge. He can also slow down time and predict the future; using these abilities activates a slow motion effect that allows players to predict movement easier, although use is limited by a meter that gradually refills. The game features eleven levels, which use Zero’s precognition as a framing device; the player’s attempts to complete each level are presented as the possible scenarios that Zero has foreseen.
Levels are split into several rooms; to proceed, the player must kill every enemy in a room within a time limit using their sword, throwable objects like lamps and pots, or environmental hazards like lasers. Aside from occasional bosses, each enemy dies in a single hit. Certain levels feature unique game mechanics, such as a stealth mission in a nightclub, a motorcycle chase mission, and a mission featuring an alternate player character. There is no health; being hit results in instant death, and the player must restart from the last checkpoint. The gameplay has been frequently compared to Hotline Miami (2012), as both games feature levels filled with enemies, one-hit kills, and require players to determine their chosen route strategically.
In between the main levels, the player converses with non-player characters (NPCs), such as the psychiatrist and a young girl who Zero befriends. The game features a real-time dialogue tree system in which the player chooses responses in their conversations, and they can interrupt an NPC’s dialogue at any time. Although they do not change the overall plot, the player’s dialogue choices can affect events that occur later in the game; for example, one boss fight can only be activated by repeatedly interrupting the psychiatrist and disobeying his orders. A May 2019 update added two additional game modes. Hard mode features more difficult levels with new enemy varieties, reworked bosses, and additional challenges. Speedrun mode challenges the player to complete every level in the fastest time possible, with the options to modify enemy behavior and skip cutscenes.