@Override
    public void execute(String[] args) {
        if (args.length < 1) {
            System.out.println("No argument specified. Please specify 'anj', 'dan' or 'debug'");
        } else if (args[0].equals("anj")) {
            Physics.setPhysicsMode(new PhysicsAnj());
            System.out.println("Now using anj's physics.");
        } else if (args[0].equals("dan")) {
            Physics.setPhysicsMode(new PhysicsDan());
            System.out.println("Now using dan's physics.");
        } else if (args[0].equals("debug")) {