[Flyndaran]

Dreaming Martians:

Suspended animation survivors of a dying Mars project their super science boosted minds to contact and influence humanity. They reach out for help, voluntary or otherwise. Controlling through dreams and possession they develop secret organizations to focus humanity on reaching Mars.

The twist is that they contact 1000s of Earths in multiple time lines but don't know which one is "near enough" to help.
They can't even be sure that seeming radically different physical laws aren't merely local Earth/human divergences.
Not until a sizeable human expedition finally sets foot on Mars do they know such humans are truly on their Mars or not.

If they discover the secret of any world jumpers, they would bring their entire species' focus onto making them help.

(Sorry if this idea has already been created somewhere.)