She debuted in Mortal Kombat X (2015) as the daughter of martial arts actor Johnny Cage and Special Forces officer Sonya Blade.

[4][5][6] Kittelsen has however stated that NetherRealm Studios had already worked on a considerable amount of the creation of the new MKX cast, and in a 2015 interview with Den of Geek, he shared: "[The] younger characters like Cassie appealed to me from a more human angle — they're badasses, but how the heck is anyone a KID in this universe?

"[4] Introduced as one of four second-generation Mortal Kombat fighters, described by Wesley Yin-Poole of Eurogamer as a "quartet of daddy issue-riddled newbies", Cassie is the daughter of Johnny Cage and Sonya Blade.

[7][8][9] A teenager growing up in Los Angeles and raised in a celebrity-obsessed culture, Cassie is "kind of aware that her dad is sort of an icon of direct-to-video movies".

"[5] Her official MK11 biography reads: "The offspring of Johnny Cage and Sonya Blade laid the smackdown on Shinnok a few years back, but even that wasn't enough to escape the shadow of her legendary parents.

[11] An early sketch by concept artist Justin Murray showed Cassie as a "robotix [sic] engineer" with spiked, pink hair and a massive hand-operated mechanical arm.

[12] Another concept depicted her as a muscular MMA-style brawler with long, pink hair and wearing a customized leather sports bra and panties, tall, black boots and fighting gloves with a personalized logo of her initials framed inside the outline of a star.

[15] Later, following the April 2015 release of Mortal Kombat X, she said in an interview with Fox Sports that her camp was looking into legal options, reaffirming her belief that "Cassie Cage is 100-percent me," and added, "Who doesn't want to be a bad ass in a video game?

Cassie's design in Mortal Kombat 11 features her in three new outfit variations: militaristic garb, heavy white battle armor, and a hot pink visor and track jacket, respectively.

[11] Serving as the main character of MKX's story,[19] Cassie is playable in the game's twelfth and final chapter, in which she fights Sindel, Kitana, and D'Vorah before battling and defeating Corrupted Shinnok.

[40][41] Under Raiden's orders, Cassie leads a task force assembled by her father and composed of a new generation of combatants—Jacqui Briggs (her best friend), Takeda, and Kung Jin.

[46] In Mortal Kombat 11, two years after defeating Shinnok, Cassie is promoted to Commander and leads a Special Forces strike team[47] alongside Sonya and Jacqui in assaulting the Netherrealm.

[49] When the Black Dragon cartel and Cyber Lin Kuei warriors attacked the Special Forces headquarters, Cassie fought to keep her parents' younger selves safe, but Kano ultimately captured them.

Having put a tracker on Kano's helicopter,[50] Cassie leads the surviving Special Forces members in weakening the Black Dragon and rescuing her parents' younger selves.

[52] In her non-canonical arcade ending, after defeating Kronika and attaining her god-like power, Cassie resurrects Sonya so she can retire peacefully and maintains her position as a Special Forces commander instead of becoming the new keeper of time.

[54] Cassie is a supporting character in DC Comics' Mortal Kombat X: Blood Ties weekly prequel miniseries that is set before the in-game storyline.

[6] Cassie is then absent from the series until chapter eighteen, where she is imprisoned in a dungeon on Shang Tsung's island and is described by Havik as "the heir to an ancient warrior power", in reference to her father Johnny Cage's lineage.

"[66] Suriel Vazquez of Game Informer wrote that in comparison to Burch's voice work in MKX, Lindbeck's performance made Cassie sound oddly younger, "less nonchalant and more juvenile", which "seemed to hamper that cool demeanor I'd come to love about her.

In 2022, Dot Esports wrote that Cassie "has been praised for her singular personality and the gender representation she embodied,"[22] and rated her among the series' five best female characters on the grounds that she "amplifies the best qualities of both [Johnny Cage and Sonya Blade].

"[47] Lucas Sullivan of GamesRadar praised the game's overall "depictions of strong women, particularly Sonya Blade, Cassie Cage, and Jacqui Briggs" as "some of the most grounded, believable, and most importantly relatable portrayals I've seen".