Why? And "it's not supposed to be" isn't an answer.
There is putting your own spin on a character, and then sacrificing basically everything about a character completely nonsensically.
Examples of putting your own twist on a character:
- Nolan's Batman, which is gritty and noirish but still maintains the parents dead/doesn't use guns/life war on crime/struggles to keep life and Batman in check element
- Brainiac in the DCAU being from Krypton to add a different spin on the Brainiac/Superman war
- Mr Freeze in B:TAS
Examples of sacrificing the entire point of the character to 'put your own spin' on it:
- The Sylvester Stallone Dredd movie in which he takes off his helmet
- Man Of Steel, in which Superman indiscriminately destroys the entire world around him without once thinking about saving civilians (on camera)
- Deadpool showing up in Wolverine and then
having his mouth sewn shutCan you do dark Superman? Sure you can. You could probably even do dark Superman without sacrificing the character's core values.
But the question is
why? What is the point in dark Superman? He's Superman. He's the big blue boy scout. That's his whole deal. If you're wanting to make a dark, realistic, gritty superhero movie, why did you choose the Truth, Justice and the American Way guy?