"When Aitim Neli said alien, it may have been implied that we're from another planet in this universe; that is not so. We are from another universe altogether, and our interuniversal transportation method is such that most places we can land are hard vacuum. For exploration, we can open portals anywhere in space, but where a portal leads to is a deterministic function of where it was opened from, relative to this planet's gravity well, so the constraint here is finding a portal that does not lead to hard vacuum. It's doable, we expect it to take a few years to do, but it means such doors will not respect country boundaries. We will not favour any nation over any other so we're precommitting to completely blocking access to a world should conflict arise due to a portal. We will leave the logistics of preventing a war to you.
"In addition to this, however, we can teach you magic. We will do so, as well as explain the details of everything else in more depth, to a group of greens that must be balanced so as to not give out political advantages to anyone. The logistics of assembling such group we also leave to you; once this group is assembled, we can go anywhere in the world to teach it.
"As an example of what our magic can do, we're turning the poles habitable and will soon be able to season them, so other worlds are not the sole resource we have available to deal with your population problems. We also intend to make everyone who wants it immortal, and we are not planning to leave you until we're confident that, with the resources you have available, you will not run into population problems before you figure out your own methods of colonising new planets.
"I will reiterate that we will not favour any countries and anyone attempting to cheat this or get any sorts of advantages over anyone else will find themselves with much fewer privileges than anyone else. I trust that you will not make the mistake of expecting me to have disclosed every resource available to us and to be easily tricked, fooled, or worked around."