The director, Len Wiseman, explains in an interview with ScreenRant:
You said that you wanted to stay a bit closer to the Philip K. Dick story. How do you think you’ve done that with this film?
It’s a combination of more of a tone that I’d say is familiar with with the short story. Our biggest difference with the Verhoeven film is that we don’t travel to Mars. Which – the book never goes to Mars, as well. They talk about it, but it all takes place on Earth, and it’s actually, for those who know the book, the imminent threat is actually about invasion on Earth. And so we incorporated a lot of those ideas. But I really think it’s a fun combination of a lot of things that are familiar from the story, things that are familiar from Verhoeven, and things that are entirely original to our own film.
From an interview with ScreenCave:
... the short story actually never travels to Mars. The threat is actually an invasion to Earth… Quaid or Quail is put in position to hopefully stop this invasion from happening to Earth. But Dan O’Bannon, who I think was the first writer on that one, took creative license to go in the other way of creating the alien aspect of it.
... When people go, ‘Well if this doesn’t go to Mars then it’s not really inspired by Philip K. Dick.’ I go, ‘Wow, you guys. It didn’t even go to Mars.’ ...
From an interview with MTV:
Will we see Mars?
We won't see Mars. And I got to say, it's one of the things that attracted me to the script, because I really, I along with a lot of other people, I really loved the Verhoeven film. I was very skeptical on just the reboot, just the idea. And until I read the script, with a lot of speculation going, it takes it in such a different direction from that film. Because it didn't go to Mars, funny enough, is why I was interested. And it's also just like I said: It plays a little bit into the threat of what the Philip K. Dick story had of, much more of bringing the threat back, really Doug's mission to save Earth, not Mars.