Quote (SpaceEngineer)
Did they crashed a big comet onto Mars
Yes, they crashed LOTS of comets into mars, burrowed huge holes (moholes) to tap into the "hot" depths of the mantle, built huge orbital mirrors (upgraded later to the soleta that was also used like a huge laser to burn the surface and release CO2 into the atmosphere), and tinkered with lots of micro organisms to modify the ground in order to make it more friendly to agriculture as the original soil had too much salts and was extremely poor.
They eventually captured another asteroid to replace the original Deimos