Walker is designed to be the protagonist of a video game experience which challenges the player emotionally through its exploration of discomforting themes associated with the efficacies and consequences of war on its combatants.

He believed that this provides greater narrative depth as Walker's experiences explore the extent of a soldier’s humanity and the impact of his psyche from the difficult choices he has to make.

In an interview with GamesRadar, lead writer Walt Williams explained that the development team of Spec Ops: The Line desired to do a "dramatic, more raw war story", something that no other entity in the video game industry was attempting at the time.

Lead designer Cory Davis described the team's attempt behind such a characterization to be "tough", as they wanted to express as strongly as possible how Walker would evolve from a "blank canvas" to a psychologically damaged person after experiencing some calamitous events within the story.

Walker uses lethal force not because he wants to defeat Konrad, but because he is determined to convince himself that he is the hero of the story; his desire to be a "good man" and his misguided conviction that every bullet he fires makes the world a better place instead results in further ruin and senseless loss of life around him.

[3] In his book Significant Zero: Heroes, Villains, and the Fight for Art and Soul in Video Games, Williams revealed that Walker was originally supposed to pursue a still-living Konrad to the top floor of Dubai's tallest skyscraper.

Williams explained that Walker's unstable psychological state is due in part to his denial over the atrocities he unwittingly committed against innocent civilians earlier in the narrative.

This connects players with Walker at an emotional level that very few shooter games will reach in North's opinion, as soldier characters are often portrayed in an overly simplistic manner as individuals who are seemingly invincible physically and mentally.

[6] Captain Martin Walker is a Delta Force operator who leads a three-man squad consisting of himself, First Lieutenant Alphonso Adams, and Staff Sergeant John Lugo to undertake what initially appears to be a recon mission, designed to reconnect with the 33rd Infantry Battalion of the United States Army who are trapped in a sandstorm-ravaged Dubai.

A pivotal moment which occurs halfway through the game's narrative marks the tipping point of Walker's descent into madness and implicates him in the killing of civilians through the deliberate use of chemical weapons at a heavily fortified location called the Gate.

After the mortar is fired and the Gate's defenses are breached, Walker's squad walk through the carnage they have caused, and discover that civilians that were taken from the Nest have also burned to death alongside the 33rd soldiers who were defending them.

Walker's squad eventually encounters another CIA agent named Riggs, who directs them into assisting his sabotage of the city's key infrastructure to wipe out the remaining population of Dubai, with the goal of covering up the 33rd's prior atrocities and protect the United States' international reputation, though hinted he knew even before the water heist.

Walker and his squad survive the crash, but he loses Lugo to a civilian lynch mob, and later Adams to a contingent of the 33rd outside a tower in downtown Dubai where Konrad's penthouse is located.

[7] In an article written for PopMatters, G. Christopher Williams offered a less enthusiastic view of the creative direction behind Walker's story arc and opined that the set-up of the game's "win-state" that culminates in an inevitable loss is a "tragedy".

He argued that it leads to "an effort that has to be endured because the end seems as if it is almost in sight", and that "psychic suicide feels warranted" for Walker after what he has done as controlled by the player over the course of The Line.

[8] Writing for the New York Times, Chris Suellentrop criticized the game's heavy-handed handling of its dark themes and the lack of subtlety with the way it presents Walker’s obtuseness regarding the horrific consequences of his actions.

He observed that even though The Line seemingly "punishes the player for playing it" by holding up their actions as an example of their complicity in violent content within video games, it remains compelling "in spite of, or perhaps because of its attitude towards videogame violence".

[12] Geoff Thiew from Hardcore Gamer ranked Walker among a 2014 list of the most memorable soldier characters in video games, citing the exploration of his struggle with post-traumatic stress disorder and his story conveys a potent message about the veneration of warfare by popular media.