System Boost: I Build a Base in the Apocalypse

[Apocalypse + strong heroine + no romance + not a saintly do-gooder + building a base]

On her way to meet up with her best friend, she is summoned by the System to its own space and strikes a deal with it. She completes missions for one reason only: to win the 50-million cash prize. She builds an apocalypse-proof safe house, stocked with everything to eat, drink, wear, and enjoy. Then she builds the greatest survival base of the apocalypse and leads the survivors to victory.