Katana Zero is a 2019 platform game developed by American indie studio Askiisoft and published by Devolver Digital. Set in a dystopian metropolis, the neo-noir storyline follows Subject Zero, a katana-wielding assassin with amnesia who can slow down time and predict the future. Zero unravels 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, using Zero's abilities to manipulate time, dodge attacks, and take advantage of environmental hazards. In between levels, the story is told in sequences where the player converses with non-player characters through dialogue trees.
Katana Zero was conceptualized by video game designer Justin Stander, who began development of the game in 2013. He had previously developed freeware games under his studio Askiisoft, such as Tower of Heaven (2009), and conceived Katana Zero as his first commercial game. Using GameMaker Studio 2, Stander sought to make a difficult story-driven game that did not force the player to wait through dialogue and cutscenes. He focused on attention to detail and looked to films such as Sin City (2005) and John Wick (2014) for story inspiration. The development was prolonged and Stander worked mostly alone, although he recruited artists to design the visuals as well as musicians Bill Kiley and Thijs "LudoWic" Lodewijk to compose the synthwave soundtrack.
Katana Zero was released for macOS, Nintendo Switch and Windows on April 18, 2019. It sold 500,000 copies in less than a year and received positive reviews. Critics praised the gameplay—which they favorably compared to Devolver's Hotline Miami (2012)—and the visuals, writing, and music. The story divided reviewers and the unresolved ending was criticized. Several critics cited Katana Zero as one of the best independent games of 2019 and it was nominated for numerous year-end accolades.
Ports of Katana Zero were released for the Xbox One in 2020, and Android and iOS via Netflix Games in 2024. Downloadable content is in development and Stander intends to continue the fictional universe in future games.
Gameplay
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 player completes assassination contracts for a psychiatrist. Zero can run, jump, wall kick, pick up and throw items, attack using his katana, and dodge. Zero's ability to slow down time and predict the future allows the player to activate a slow motion effect, enabling them to predict enemy 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 possible scenarios Zero has foreseen.
Levels are split into several rooms, and the player must kill every enemy in a room using their sword, throwable objects, such as lamps and pots, or environmental hazards, such as 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, and an alternate player character. Any damage results in instant death for Zero, requiring the player to restart from the most recent checkpoint. Katana Zero has been frequently compared to Hotline Miami (2012), as both feature levels filled with enemies, one-hit kills, and require players to determine their chosen route strategically. Outside of the main game, there are two additional game modes: hard mode features more difficult levels with new enemy varieties, reworked bosses, and additional challenges; and speedrun mode challenges the player to complete every level in the fastest time possible, with the options to modify enemy behavior and skip cutscenes.
Story and dialogue Katana Zero follows a neo-noir-style storyline, with psychological horror and black comedy elements, set in a dystopian metropolis after a war. Subject Zero is an amnesiac veteran with precognitive abilities. He assassinates drug dealers and other targets (including a political prisoner) for his psychiatrist, who acts as his handler. The news media ascribes these killings to a serial killer known as the Dragon. Zero experiences recurring nightmares of a child, who he identifies as himself, in a hut. A scientist runs in, warns the child to hide, and is shot moments later by a soldier. He discusses his nightmares with the psychiatrist, who supplies him with a drug as treatment. Zero also befriends a young girl living next door to his apartment, and he becomes attached to her.
In between levels, the player converses with non-player characters (NPCs), such as the psychiatrist, the girl, and a Russian psychopath antagonist named V, who admires Zero's lethality. In a real-time dialogue tree system, the player chooses responses during conversations and can interrupt an NPC's dialogue at any time. Their decisions determine how much exposition is presented and how Zero is characterized; for example, Zero comes across as rude if the player repeatedly interrupts. Although they do not change the overall plot, players' dialogue choices can affect certain events, and one boss fight can only be activated by making specific decisions.
Zero and the psychiatrist's relationship becomes strained as the psychiatrist grows increasingly disagreeable and Zero suspects he is withholding information about the assassinations. Later, another clairvoyant swordsman, identifying himself as the actual "Dragon", dismembers and abducts V. Zero learns about his own past as a supersoldier known as a "NULL" and that the drug he had been taking, known as Chronos, gave him his abilities. However, it causes users to become trapped within their minds as a withdrawal symptom. Zero is tasked with eliminating the Dragon, but fails after encountering a similarly clairvoyant marksman, known as Headhunter, and is forced to kill intervening police - however, when he is eventually cornered, he is confronted by a pair of men wearing drama masks, who force him to choose whether to live at the cost of an unknown price or to die permanently at the hands of the police, with the latter leading to an alternate ending. Afterwards, Zero is tasked with destroying a bunker with confidential materials related to Chronos, and kills Headhunter. However, he ultimately spares the family hiding inside the Bunker, and, tired of being manipulated, kills the psychiatrist. The girl goes missing, presumably kidnapped by the masked men and the story ends on a cliffhanger. A flashback reveals Zero's nightmare is a memory from the war, and that he was the soldier who shot the scientist, and also worked with the Dragon, who was identified as Fifteen.
Development Conception Katana Zero was developed over six years by the indie game creator Justin Stander under the studio name Askiisoft. It was Stander's first commercial game; his previous projects, such as Tower of Heaven (2009), had been smaller freeware games. After seeing the success of Terry Cavanagh's VVVVVV (2010), Stander concluded audiences only pay attention to indie games if they are being sold. Cavanagh, like Stander, had started off making freeware games, but none were as successful as VVVVVV. Katana Zero originated from Stander's desires to create a larger project that could be sold commercially and tell a story. He began working on it in 2013 as a hobby during his sophomore year at McGill University. He used the GameMaker Studio 2 game engine and spent the first two years building simple prototypes. The game was a means of expression for Stander outside schoolwork and he spent most of his time at college developing it.
After Stander graduated in 2015, he developed Katana Zero full time. He worked on multiple projects alongside it as a precaution since he felt the chances of success were slim. The total budget was 60,000, which Stander noted was quite small for a game of Katana Zero scope. He stated: "Most of it was just not paying myself at all and cutting down costs in my own life to do nothing but work on the game." Stander worked largely on his own, although he recruited help for the art and music. The game was initially developed for personal computers (macOS and Windows). Stander decided to develop a Nintendo Switch version immediately after the system was unveiled because he saw it as a good console for indie games. GameMaker made it easy to port Katana Zero and the long development meant it was already well optimized.
Design One of Stander's goals was to make killing feel exciting and satisfying. He considered many modern games too forgiving, with enemies less powerful than the player. Finding it difficult to die in games such as Payday: The Heist (2011), Stander decided it would be easy to die in Katana Zero. He wanted the game to be difficult but fair and for the player to recognize and take responsibility for their mistakes. He continued his style of design—short levels filled with instant-death scenarios—from Tower of Heaven and Pause Ahead (2013). The one-hit-kill gameplay was frequently compared to another Devolver Digital-published game, Hotline Miami. Stander said he only played Hotline Miami once and did not remember its gameplay, but acknowledged it may have subconsciously influenced him. He named Samurai Gunn (2013), which he felt used one-hit kills effectively, as the bigger influence.
Stander wanted Katana Zero to feel cinematic and sought to subvert expectations: "As soon as you think you understand how this game is going to play out, then I just try to completely shift it on you... as soon as [you're] comfortable in [something], I try to shift things up. And I do that several times throughout the game. I really mess with the player." To maintain variety, he incorporated many enemy types, environmental traps, alternate level pathways, and set pieces. A minecart pathway inspired by Indiana Jones and the Temple of Doom (1984) took over a month to create. Stander looked to indie games that feature "tight, fast-paced, instant death combat" for inspiration, such as Trilby: The Art of Theft (2009) and Gunpoint (2013).
The art style was inspired by the neon lighting aesthetics associated with the 1980s. Recruiting artists proved challenging; Stander called himself "a terrible artist", and for two years no artists worked on the game. He found artists through the online independent developer community TIGSource, but said it was difficult to recruit high-quality pixel artists who would commit to the project. Many would only work on it for weeks or days before quitting for various reasons, such as other commitments or feeling their style did not match. Stander used the neon lighting to blend the artists' different styles. He considered being able to get an artist team to finish the game mere chance and credited the artists with motivating him to finish.
Stander focused on attention to detail and said adding a single mechanic, such as a gun turret, would require him to alter many different systems, such as the lighting, to maintain cohesion. Production value was important, as Stander wanted the engine to feel flawless. He said this meant "no bugs. Everything needs to feel like an extension of the player. When you play it, you should always feel like this is exactly what I wanted to do and that is what the character did." When developing small freeware games, he could scrutinize minute details, which would result in him spending a year to make a short, 20–30 minute game. Adapting this mentality to a full-length commercial game contributed to the prolonged development; Stander originally expected development to last a year or two. His focus on particulars demoralized him, to the point he made little progress for a year.
Writing