The lyrics speak of the things one may have gained and lost in life, written from Gilmour’s autobiographic perspective. Gilmour has said that the song is more about his early days, and leaving his hometown behind, than about the seeds of division supposedly planted in Pink Floyd’s early days.
If you listen closely to the lyrics, you can see the central theme of the song. It’s about how are you become old and start looking back at the life you had when you were young in your childhood.
The game of life is the endless river.
But we will transcend the game altogether, and reach the other side.