Ok, pay that, wasn't him saving the world.
But you get a classic story, and change everything about it...not a good start. A civilisation on Mars might have been believable when the thing was written, nowdays, not so much.
It didn't help that everyone in that movie was too mind-numbingly stupid to live.
The aliens are invincible, and you know this? Keep attacking them anyway.
And then the son decides sit and watch the military get slaughtered because he "has to do this".
Cruise can't get himself pulled into the alien machine until he shows it that he's not one of the defenceless humans they are pulling into their machines, he's one of the armed ones they are vapourising.
And the idea that the aliens had landed on earth many thousands of years ago, buried themselves in places they knew would be major cities later on for no reason, only to emerge now for no reason, and could do all that without exposing themselves to diseases which they decided to do now for no reason...nah. Rubbish.