So, the games end with the last man entering the game and that last man gets the entire pot. This is a never ending game cause the deadline gets extended with the last man. Why would anyone play this game when no one know when this game ends. I am not sure if it falls under a Ponzi scheme. I think it would be right to call it a scam.
This is a lottery game, someone will eventually win when no other person enters the game. When you play a normal lottery, your odds of winning are low but you don't call it a scam because you didn't win.