Complex sentence: Now, you have a choice of going to one of two other places controlled by other bosses which the player needs to destroy to eventually get to the final battle in the Big Core and eventually saving the earth from the climate crisis.
Split into simpler sentences: Now, you have a choice of going to one of two other places controlled by other bosses which the player needs to destroy. Eventually, the player gets to the final battle in the Big Core and saves the earth from the climate crisis.