When you start up Death Stranding 2: On the Beach, you'll be asked to enter your birthday, just like in the original game. The description for this doesn't tell you much other than it can "determine a person's experience of DOOMS" the condition that allows Sam to sense BTs. But while the original Death Stranding left it at that, Death Stranding 2 follows Metal Gear Solid 5 and leaves in a little surprise for your birthday.
As posted by Giant Bomb on Bluesky when you return to the DHV Magellan as Sam, you'll emerge on the bridge and see it's completely dark, before Dollman appears and says "happy birthday buddy" and the rest of your crew on the DHV Magellan emerge and wish you a happy birthday too… Including Sam, they're talking to you, the player.
