Using number as "index" (JSON)

JSON only allows key names to be strings. Those strings can consist of numerical values.

You aren't using JSON though. You have a JavaScript object literal. You can use identifiers for keys, but an identifier can't start with a number. You can still use strings though.

var Game={
    "status": [
        {
            "0": "val",
            "1": "val",
            "2": "val"
        },
        {
            "0": "val",
            "1": "val",
            "2": "val"
        }
    ]
}

If you access the properties with dot-notation, then you have to use identifiers. Use square bracket notation instead: Game.status[0][0].

But given that data, an array would seem to make more sense.

var Game={
    "status": [
        [
            "val",
            "val",
            "val"
        ],
        [
            "val",
            "val",
            "val"
        ]
    ]
}

First off, it's not JSON: JSON mandates that all keys must be strings.

Secondly, regular arrays do what you want:

var Game = {
  status: [
    [
      "val",
      "val",
      "val"
    ],
    [
      "val",
      "val",
      "val"
    ]
  }

will work, if you use Game.status[0][0]. You cannot use numbers with the dot notation (.0).

Alternatively, you can quote the numbers (i.e. { "0": "val" }...); you will have plain objects instead of Arrays, but the same syntax will work.

Probably you need an array?

var Game = {

    status: [
        ["val", "val","val"],
        ["val", "val", "val"]
    ]
}

alert(Game.status[0][0]);

When a Javascript object property's name doesn't begin with either an underscore or a letter, you cant use the dot notation (like Game.status[0].0), and you must use the alternative notation, which is Game.status[0][0].

One different note, do you really need it to be an object inside the status array? If you're using the object like an array, why not use a real array instead?

JSON regulates key type to be string. The purpose is to support the dot notation to access the members of the object.

For example, person = {"height":170, "weight":60, "age":32}. You can access members by person.height, person.weight, etc. If JSON supports value keys, then it would look like person.0, person.1, person.2.