Speaking to Digital Spy, the Fall filmmaker admitted that he wanted to change the screen portrayal of Greek gods, who are often played by senior actors such as Sir Laurence Olivier and Liam Neeson in the Clash of the Titans films.
"If you want live forever, you want to live forever looking young," he said. "You wouldn't want to live forever looking like you've got a catheter in your hand. With that in mind, I thought you want someone with the wisdom of a person who's lived forever but not the body of a person who's lived forever."
Of the initial plans to show an incestuous relationship among the gods, who include Zeus (Luke Evans), Poseidon (Kellan Lutz) and Athena, Tarsem said: "Incest is to much more believable if your daughter looks the same age as you. Unfortunately once I had it in the film, people balked at the idea of any flirtatiousness with Athena and we had to get rid of it."
Tarsem noted that Immortals transformed into a more "testosterone-driven" movie than he had first envisioned, with a focus on marketing the film to teenage boys.
"Unless it's a personal film you don't get everything your way. Theseus's death, I didn't want him going up into the sky, I wanted it to be much more emotional film - it was a lot more testosterone-driven than I thought," he explained.
"People just said 'Forget the women'. There were certain scenes where it was more emotional but they just said go for the violent ending. It was a lot more for women, the film I wanted, but in the end test audiences said 'Forget the women, go for the boys'."
Immortals pits Henry Cavill's slave Theseus against the tyrannical King Hyperion played by Mickey Rourke, an actor Tarsem described as "an absolute nutter".
"Usually when I make a film I want one person to try to break through, that can be a child, a diva, anything," he said. "This one was him. I wanted him to be intimidating, he had contacts on, he couldn't see very well, he doesn't like to memorise lines. You give a guy like that a fear and the tension will obviously come up."
Immortals was released in 3D, which Tarsem claimed suits his measured directorial approach.
"My style tends to lend itself to 3D because it's a bit tableauxey, a bit static," he said. "3D is made for that so we were aware of it and were taking measurements all the time. That's why I don't think it looks like a converted film."
Asked if he thinks 3D movies are here to say, Tarsem replied: "It's got teething problems, it's evolving, I don't have an opinion on it. Certain kind of things are really good for it, certain things aren't, certain people's styles aren't good for it. For Tim Burton or David Fincher it can work, but for someone like Spike Jonze or Paul Greengrass, [their style] just isn't made for 3D that much."
Immortals is out on 3D Blu-ray, Triple Play Blu-ray, DVD and download from March 5, 2012. Pre-order your copy now at www.play.com