The Last Mission

It's been 300 years since humanity has fled from the Ai that destroyed Earth with
nuclear weapons. Most of the humans that remain live underground, in the caverns
of Mars. A small band of specially chosen soldiers is given a mission to reclaim Earth,
to see if it's fit for colonization. They've trained their whole lives for this mission.
Still, nothing in the cosmos could possibly prepare them for what they are about to
unearth.
The human brain can only fit so much stuff in it, so instead of learning a little bit
about a bunch of topics, they chose a bunch of soldiers and make them learn a
lot about a smaller number of topics. As a unit, this made them stronger... But if
someone died, that knowledge died with them.
People thought that meeting intelligent life would bring peace. They were wrong.
When the soldiers landed on the planet's surface to investigate something that
should not be flourishing human settlements. The squad encounters very bad and
dangerous circumstances and suddenly survival became the most requested need.