Two words: Holy. Shit. Mother Base is huge, literally and figuratively. You can research and develop new or improve existing equipment for your missions. Recruit/kidnap enemy soldiers in order to grow your army. Level up your support team and you can call for supplies and airstrikes during your missions, or even manipulate the goddamn weather to your advantage. Keeping your army's morale up is important, and be sure to shower (yes, you can actually take a shower in Mother Base) in between missions so you don't disgust your comrades. INVASIONS...or infiltrations, to be more accurate, of other players' Forward Operating Bases (which are the online extensions of Mother Base, and are optional). You can steal supplies or soldiers from these bases, but be careful not to be detected. Players can infiltrate your FOB even during a mission. Be sure to keep your security and defenses up. My hype level is beyond orbit at this point. It's not even in the solar system anymore.