2048, as I would play it (with a little help from http://maythesource.com/2012/06/26/simulating-keypresses-keystrokes-with-javascript-for-use-with-greesemonkey-etc/)

twopower.js

(function(){
var gridElem = document.getElementsByClassName("grid-cell")

function FakeInputManager(){}
function FakeScoreManager(){}
function FakeActuator(){}
FakeInputManager.prototype = {"on": function(){}};

FakeScoreManager.prototype = {"get": function(){return 0}, "set": function(){}};

FakeActuator.prototype = {"actuate": function(){}, "continue": function(){}, "clearContainer": function(){}, "addTile": function(){}, "applyClasses": function(){}};

var gm = new GameManager(4, FakeInputManager, FakeActuator, FakeScoreManager);

var moveKey = [38, 39, 40, 37];

var lastMove = 0;

function solveTick() {
	var beginScore = gm.score;
	var highestMove = (lastMove + 1) % 4;
	var highestScore = 0;
	for (var i = 0; i < 4; i++) {
		updateGrid();
		gm.move(i);
		if (gm.score > highestScore) {
			highestScore = gm.score;
			highestMove = i;
		}
		gm.score = beginScore;
	}
	updateGrid();
	gm.move(highestMove);
	pressKeySim(moveKey[highestMove]);
	lastMove = highestMove;
}
function pressKeySim(key) {
	var keyboardEvent = document.createEvent("KeyboardEvent");
	var initMethod = typeof keyboardEvent.initKeyboardEvent !== 'undefined' ? "initKeyboardEvent" : "initKeyEvent";


	keyboardEvent[initMethod](
						"keydown", // event type : keydown, keyup, keypress
						true, // bubbles
						true, // cancelable
						window, // viewArg: should be window
						false, // ctrlKeyArg
						false, // altKeyArg
						false, // shiftKeyArg
						false, // metaKeyArg
						key, // keyCodeArg : unsigned long the virtual key code, else 0
						0 // charCodeArgs : unsigned long the Unicode character associated with the depressed key, else 0
	);
	document.dispatchEvent(keyboardEvent);
	console.log(key);
}

function updateGrid() {
	gm.grid.eachCell(function(x, y, val) {
		theCell = document.getElementById("tile-position-" + x + "-" + y);
		if (theCell == null) {
			gm.grid.cells[x][y] = null;
		} else {
			gm.grid.cells[x][y] = new Tile({x: x, y: y}, parseInt(theCell.textContent));
		}
	});
}

setInterval(solveTick, 500);
})();