It was thought that Batman v Superman: Dawn of Justice couldn't be grittier, but the original script sought to challenge those beliefs.
Batman v Superman: Dawn of Justice, directed by Zac Snyder, came out in 2016 and was met with mixed reviews with both sides arguing over just how dark a superhero movie should be. However, according to the original screenwriter for the 2000s project of the film, things could've been a lot different if that version of the movie premiered.
The movie was set to be directed by Wolfgang Peterson with Colin Farrell as Batman and Jude Law as Superman. Sadly, the script was later revised because the new writer felt that the dark tone was too ahead of its time for a superhero movie.
The original script would've started with a retired Bruce Wayne attending Alfred's funeral. Batman seemed to put the past behind him to start a future with his wife until the Joker kills her.
The second scriptwriter would eventually revise this idea for the script because he felt that the tone and ideas "weren't landing quite in the way I think we imagined when we put them on the page." Fearing that what sounds good on-page wouldn't work well in the real world even though they have used dark inspiration for their movie.
The movie would go on to have other problems as well. Jude Law would leave the project because he didn't like the way his suit looked. At least Colin Farrell was able to come back into the universe as Penguin in the upcoming Batman movie. Now fans are only left to imagine what could've been a more gritty experience.
Source: IGN