var Player1 = function(){
this.x = 400
this.y = 700
this.speed = 10
this.xSpeed = 0
this.ySpeed = 0
}
var Player2 = function(){
this.x = 400
this.y = 800
this.speed = 10
this.xSpeed = 0
this.ySpeed = 0
}
И тебе не нужно здесь два конструктора создавать. Достаточно одного Player
var Player = function(settings) {
this.x = settings.x || 0;
this.y = settings.y || 0;
this.speed = settings.speed || 0;
this.xSpeed = settings.xSpeed || 0;
this.ySpeed = settings.ySpeed || 0;
}
var player1 = new Player({x: 400, y: 700, speed: 10});
var player2 = new Player({x: 400, y: 800, speed: 10});