The Player (judging by the earlier games) is a human sent out to explore new planets to colonize after earths destruction. The player seems very strong and durable perhaps because of his/her armoured suit. the suit the player wears may provide the HUD (Heads Up Display) as when he/she dies it says "lifesupport offline"
The suit may provide oxygen, this may be why it says "life support offline" when you die, because you suffocate when the suit has taken enough damage. the suit also seems to be able to wear other armor on top of it, which may mean the suit is simply light-weight or exo-skeleton like.
The player goal is to end the neverending war on a new planet, and goes to great lengths to help the planet.