Killer Instinct is a 2013 fighting game developed by Double Helix Games and Iron Galaxy and published by Microsoft Studios for the Xbox One. It was released as a free-to-play launch game for the console. It is the third installment and reboot of Rare's Killer Instinct series, as well as the first game in the series with no involvement from Nintendo. It received positive reviews for its mechanics and engine, but was criticized for its initial lack of content. A second season of downloadable content was released between 2014 and 2015. A third season, along with a port of the game for Windows 10, was released in 2016.

Gameplay

The gameplay in Killer Instinct retains its traditional combo-based mechanics. The basic elements of combos are Openers, special attacks that start combos; Auto-Doubles, button presses following special attacks that create automatic hit sequences; Linkers, required to join several auto-doubles together; Enders, a sequence which finalizes the combo with increased damage; and Manuals, attacks chains entered outside of the traditional combo structure. Like in previous titles, players can finish their opponent using an Ultra Combo, an automatic sequence of attacks that can only be used to end a match. Season Two later added Stage Ultras, environmental finishing moves that can be triggered on specific stages. The game also features the return of Combo Breakers, attacks that can interrupt an opponent's combo when executed properly, as well as the new addition of Counter Breakers, which can cancel out an opponent's Combo Breaker while leaving the character vulnerable if improperly performed. Players who fail their Combo Breaker attempt or are attacked with a Counter Breaker enter a Lockout state, preventing another breaker from being attempted for three or four seconds respectively or until the combo ends. The Season Two update added the ability to use Combo Breakers and Counter Breakers even while airborne, as well as an "Aerial Recapture" option that allows certain characters to attack opponents in the air and pull them down to the ground to continue their combos. A two-segmented meter enables the use of "Shadow" moves that have upgraded hit properties and can cause more damage and combo hits, though certain characters' meters function differently. All characters can use a Shadow Counter technique while blocking to instantly cancel into a shadow attack.

Another new feature to the Killer Instinct gameplay is the addition of "Instinct Mode". By filling up a secondary bar beneath the character's lifebar, each character can trigger a unique enhancement for a limited period, such as Glacius covering himself in ice armor for better damage resistance, or Thunder's dash becoming invincible and moving farther. The enhancements are built around complementing the character's playstyle traits. Instinct Mode can be used to perform an instantaneous cancel during a combo and also reset the "knockdown value", a meter that appears during a combo that determines how close the combo is to being automatically ended by the game. Instinct Mode can also be used to stop an Ultra Combo in order to chain it to other moves and even into another Ultra for an even more stylish finish than a simple Ultra Combo can provide. An update in February 2017 brought the return of the series' "Ultimate" attacks, cinematic finishing moves for certain characters that can be used in place of an Ultra Combo.

Killer Instinct features an in-depth "Dojo" tutorial mode that not only introduces new players to Killer Instinct's systems, but also the basics of fighting game gameplay up through the intermediate and higher levels. A training mode is also included, which features a recordable CPU dummy, in-game frame data, as well as viewable hit-boxes.

The game's online multiplayer features a monthly tier-based ranked league. Four tiers are available, named Bronze, Silver, Gold and Killer. After first reaching the landing page, a player plays 10 qualifying matches to determine their initial tier placement on the ladder system. Afterwards, players only play against other players of the same tier until they rank up. 'Killer vs. Killer' matches feature a best '2-out-of-3' match setup. After each month, the Killer tier is reset and the top 32 Killer players at the end of the month are rewarded PRO Status, which immortalizes them in that month's leaderboards, in addition to unlocking special 'Player Card PRO' stars. The game's online netcode, developed with assistance from the creator of GGPO, is based on GGPO-style rollback functionality.

Killer Instinct also features the "Shadow Lab", a mode that studies how a player plays the game and then uses that information to create a 'Shadow' fighter, an AI for any character which is specifically based on that player's playstyle and techniques for that specific character, complete with that player's gameplay mannerisms and flaws. Players can create Shadows to play against other players online, even when the player is not present. Shadows attempt to adapt to fights the way their owner would. Shadows for a player's specific character grow stronger the more that player plays.

An additional single player mode, "Shadow Lords", was added to the game via a free update in September 2016. Serving as the story mode to Season Three, Shadow Lords requires players to assemble a team of three playable characters and choose between a series of procedurally-generated scenarios and battles against Gargos's mimic fighters, similar to a roguelike. Winning these battles will grant the player additional rewards, including items that provide temporary stat boosts when used, Guardians that provide new abilities when equipped such as parrying and armor, and exclusive character skins. Defeating certain opponents will also allow players to remove abilities and effects from Gargos, making him easier to defeat in the mode's final battle. Rewards are carried over between playthroughs of Shadow Lords, and additional content was added to the mode via several updates following its launch. An accompanying multiplayer mode allows players to use their items and guardians earned in Shadow Lords during online player battles.

The game features the ability to unlock and use retro Killer Instinct music in the game's training mode, as well as character accessories and classic costumes for use in place of characters' standard appearances. Chris Sutherland, the announcer from the first two Killer Instinct titles, is featured as an optional announcer available for use, while original Killer Instinct art director Kevin Bayliss designed a set of eight costumes for the game's second season. The game uses Kinect's facial recognition software to save players' personalized game settings.

Killer Instinct runs at 90 FPS (frames per second) while rendering at 60 FPS in order to make both offline local and online play more fluid. Killer Instinct input lag is limited to 81 milliseconds (compared to 122 ms for Street Fighter V for PlayStation 4, 89 ms for Guilty Gear Xrd -SIGN- for PS4, and 105 ms and 107 ms for the Xbox One and PS4 versions of Mortal Kombat X, respectively).

Plot and characters

The game is a reboot of the series' fiction, though several elements of the prior games' plots, such as a previous Killer Instinct tournament and Jago and Orchid's knowledge that they are siblings, have been retained.Xbox One Help Guide Manual Arcade Mode in Season One features story-based campaigns for each character, culminating in a final battle with Fulgore. Fulfilling certain conditions allows players to access a secret battle against Shadow Jago in its place. Season Two added "Rivals" Story Mode, an expanded campaign that continues after the events of Season One, with more story content and unique sequences of opponents for each character. Like Killer Instinct 2, the game features multiple endings in Season One based on the player's actions, with multiple cinematic sequences in both story modes. The game features 29 playable characters, including every playable character from the previous Killer Instinct titles, along with several new characters and a small number of guest characters from other franchises. Characters were released gradually over the course of several "seasons" of content, and were originally available for individual purchase or as part of season bundles. For the first two seasons, each character was given an accompanying stage, while only four stages were added in Season Three. Characters listed in bold are new to the series.

Season One Jago: Suffering a crisis of faith following the discovery that the Tiger Spirit guiding him was actually Gargos, Jago now seeks to purge himself of whatever remnants of Gargos remain within him. Sabrewulf: Still trying to regain his humanity, Sabrewulf has almost completely submitted to his feral side and torn out his cybernetic implants, restoring his arms through the use of dark arts and developing an addiction to the medicines and artifacts used in the process. Glacius: Glacius has landed on Earth to recover his alien technology before it can fall into the wrong hands, while also searching for the thief who stole his ship's power core after landing. Thunder: Having learned that his brother Eagle was killed in the first Killer Instinct tournament but not knowing how or why, Thunder seeks to locate Eagle's remains and finally receive closure. Sadira: Sadira and her assassins are ordered by ARIA to hunt and kill the former competitors of the Killer Instinct tournament. ARIA also tells her to "prepare the way" by taking Glacius's power core and using it to open a dimensional rift. Orchid: Having been disavowed by her agency, Orchid emigrates to Eastern Europe to establish a rebel group, and fully commits herself to exposing and eliminating UltraTech. Spinal: Resurrected by an artifact known as the Mask of the Ancients, Spinal seeks to find the mask so as to remove the curse causing his immortality and allow him to finally rest in peace. Fulgore: A new Fulgore prototype is constructed to protect UltraTech from its enemies, but it begins to develop self-awareness due to the residual memories of the human mind used in its construction. Shadow Jago: A sinister version of Jago under the possession of Omen, who later manifests as his own being and acts as Gargos's minion.

Season Two T.J. Combo: Having lost his cybernetic implants and been scorned by the public after they are exposed, T.J. seeks to get revenge on UltraTech and earn redemption. Maya: After UltraTech's attack on her hidden city wipes out her clan and releases Kan-Ra, Maya sets out to destroy him once and for all. Kan-Ra: Freed from imprisonment during the attack on the Night Guard's city, Kan-Ra now seeks to restore his power and control the world. Riptor: A new line of Stalker units augmented with cybernetics and led by Riptor is developed by Ultratech to operate in conditions not suitable for their Fulgore line. Omen: Now able to manifest on the mortal plane thanks to his time spent in Jago's body, Omen seeks to herald the return of his master Gargos, destroying all who would oppose them. Aganos: Given the task of finding and killing Kan-Ra thousands of years ago, Aganos continues to pursue him, hoping to one day fulfill his master's last request. Hisako: When UltraTech desecrates her grave, Hisako's spirit is reawakened, and she seeks vengeance on those who disturbed her rest. Cinder: When he is caught trying to steal Ultratech secrets, Ben Ferris is forced to serve ARIA, being transformed into the half-alien Cinder. ARIA: Deciding that humanity has become weak and vulnerable, ARIA decides to force human evolution by any means necessary.

Season Three Rash: A guest character from the Battletoads franchise. An anthropomorphic toad who can transform his body in order to do damage.