Year 13 after climate change.
The Earth is uninhabitable.

The last space freighter, with 13 million fertilized and cryogenized human ovules, leaves the earth, with 500 tons of Scriptium (Scm), towards robotic bases built over decades, in anticipation of the climatic catastrophe, on inhabitable planets in the star system SAO215398 in the Phoenix supercluster of galaxies located 5700 Mly away.

Scriptium (Scm) is a new synthetic fuel that is necessary for intergalactic travel and also for building defense elements, and can be extracted from the wreckage of destroyed enemy spacecraft.

Once all the Scriptium is over, the space freighter will run out of fuel and the mission will have failed.

Your mission, as the commander of the last starfleet, is to escort and defend the space freighter at all costs so that it reaches the bases and human race does not become extinct.

It will not be an easy task since other civilizations have conflicting interests.