In the book Red Mars by Kim Stanley Robinson (my favorite Sci-Fi book series of all time), the first life that spread and took hold on Mars was Lichen (that dry flaky moss like stuff you see on rocks around a beach). That shit will grow anywhere.

Also if you like terraforming games, I recommend Terra Nil. They've had a few updates since I wrote this and the game is a lot longer now:

https://battlepenguin.com/gaming/terra-nil-final-fantasy-xvi/#terra-nil