Homo Ludens is a book written in 1938 by Dutch author John Huizinga. As the title suggests, he discusses the importance of play in culture and society as a whole. Furthermore, the phrase can also be translated as the "playing man." But how does the concept of Homo Ludens relate with Death Stranding?
Even when he was still involved with Metal Gear Solid, Hideo Kojima is already interested in evolution and those who have been keen would have noticed how he integrated concepts of evolution into MGS.
Now that he has his own studio and developing a new game, Death Stranding, Kojima's interest and love affair with evolution have not diminished one bit. In fact, his studio and Death Stranding itself have been loaded with references to evolution.
First, the mascot of Kojima Productions is called Ludens and their tagline, are obviously a reference to this belief. In a way, his studio is also a metaphor of that evolution from a simple celled organism to becoming an intelligent and advanced organism.
In relation to Death Stranding, it can be remembered that Norman Reedus said in a previous interview that players will not be playing him in the game but will actually be him. Kojima confirmed it in a way when he said that the mascot - Ludens - represents all the players. When you look closely at Luden's face in the video, it actually has a resemblance with Reedus. With that, both Kojima and Reedus are saying is that all people are players giving the tagline "We are Homo Ludens" some sense.
The statement also shows that Kojima is stating the obvious that players are the next state in evolution and, at the same time, we are all human beings. Connect that with Norman Reedus in the game as the first Adam and the players as Reedus himself and you get some hints what Death Stranding is all about - the evolution of man in a different version of the Creation narrative.