So far as I can see, that only thing that seperates manga and comics are the form of drawing and the plot depth, and in Watchmen's case, they don't get much deeper. So I apologize in advance if I'm wrong and it isn't.
Anyway, I recently found out about Watchmen from an online friend. I read it and I was amazed.
Post relevant comments here if you enjoyed it.

(Source: Wiki Watchman)
Watchmen is a twelve-issue comic book limited series created by writer Alan Moore, artist Dave Gibbons, and colorist John Higgins. The series was published by DC Comics during 1986 and 1987, and has been subsequently reprinted into collected form. Watchmen originated from a story proposal Moore submitted to DC featuring superhero characters that the company had acquired from Charlton Comics. As Moore's proposed story would have left many of the characters unusable for future stories, managing editor Dick Giordano convinced the writer to create original characters instead.
Moore used the story as a means to reflect contemporary anxieties and to critique the superhero concept. Watchmen depicts an alternate history where superheroes emerged in the 1940s and 1960s, helping the United States to win the Vietnam War. The country is edging closer to a nuclear war with the Soviet Union, freelance costumed vigilantes have been outlawed and most costumed superheroes are in retirement or working for the government. The story focuses on the personal development and struggles of the protagonists as an investigation into the murder of a government sponsored superhero pulls them out of retirement, and eventually leads them to confront a plot to stave off nuclear war by killing millions of people.
Creatively, the focus of Watchmen is on its structure. Gibbons used a nine-panel grid layout throughout the series and added recurring symbols such as a blood-stained smiley. All but the last issue feature supplemental fictional documents that add to the series' backstory, and the narrative is intertwined with that of another story, a fictional pirate comic titled Tales of the Black Freighter, which one of the characters reads. Structured as a nonlinear narrative, the story skips through space, time and plot. Watchmen has received critical acclaim both in the comics and mainstream press, and is regarded by critics as a seminal text of the comics medium. After a number of attempts to adapt the series into a feature film, director Zack Snyder's Watchmen was released in 2009.
Story
Watchmen is set in an alternate reality which closely mirrors the contemporary world of the 1980s. The primary difference is the presence of superheroes. The point of divergence occurs in the year 1938. Their existence in this iteration of America is shown to have dramatically affected and altered the outcomes of real-world events such as the Vietnam War and the presidency of Richard Nixon. In keeping with the realism of the series, although the costumed crimefighters of Watchmen are commonly called "superheroes", the only character who possesses obvious superhuman powers is Doctor Manhattan. The existence of Doctor Manhattan has given the U.S. a strategic advantage over the Soviet Union, which has increased tensions between the two nations. Eventually, superheroes grow unpopular among the police and the public, which has led to the passage of legislation in 1977 to outlaw them. While many of the heroes retired, Doctor Manhattan and The Comedian operate as government-sanctioned agents, and Rorschach continues to operate outside the law.
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