function Update() {
if (Input.GetKeyDown(KeyCode.Escape)) {
//Твоя функцыя
}
else {//При нажатии на кнопку вторый раз, функцыя действует наоборот
//Твоя функцыя наоборот
}
}

var a : boolean = false;
var b : boolean = true;

function Update () {
if (a == true) {  
//сюда свой код, когда меню открыто
}
if (a == false && b == true) {  
if (Input.GetKeyDown(KeyCode.Escape)) {  
a = true;
b = false;
}
}
if (a == true && b == true) {  
if (Input.GetKeyDown(KeyCode.Escape)) {  
a = false;
b = false;
}
}
if (Input.GetKeyUp(KeyCode.Escape)) {  
b = true;
}
}

var Player : Transform;
var spawnObject: Transform;

var guiEnter : GUISkin;
var sound : AudioClip;
var Loading : GameObject;
var Enter = 1;

private var hostData : HostData[];

function OnNetworkLoadedLevelServer () {
//    Network.Instantiate(Player, spawnObject.position, Quaternion.identity, 0);
Network.Instantiate(Player, transform.position, transform.rotation, 10);
Debug.Log("Server: Spawn Player");
}
function OnNetworkLoadedLevelClient () {
//    Network.Instantiate(Player, spawnObject.position, Quaternion.identity, 0);
Network.Instantiate(Player, transform.position, transform.rotation, 10);
Debug.Log("Client: Spawn Player");
}

function OnPlayerConnected(Player: NetworkPlayer) {
Debug.Log("Player " + playerCount++ + " connected from " + Player.ipAddress + ":" + Player.port);
}

function OnPlayerDisconnected (player : NetworkPlayer) {
Debug.Log("Disconnecting: " + Network.connections[0].ipAddress+ ":" + Network.connections[0].port);
Network.RemoveRPCs(player, 0);
Network.DestroyPlayerObjects(player);
}

function OnConnectedToServer() {
if(Network.isServer) {
OnNetworkLoadedLevelServer();
}
if(Network.isClient) {
OnNetworkLoadedLevelClient();
}
}
function OnMasterServerEvent(mse:MasterServerEvent) {
if (mse == MasterServerEvent.RegistrationSucceeded) {
}
}

function OnGUI() {
if (Enter == 1) {
GUI.skin = guiEnter;
if(GUI.Button(Rect (Screen.width/2 - -325,Screen.height/2 - -225,54,30), "")) {
if(Input.GetMouseButtonUp(0)){
OnConnectedToServer();
audio.clip = sound;
audio.Play();
Enter = 0;
Loading.guiTexture.enabled = false;
gameObject.Find("Loading").GetComponent("AudioListener").enabled = false;
gameObject.Find("Camera").GetComponent("Interface").enabled = true;
gameObject.Find("Camera").GetComponent("Interface_Chat").enabled = true;
}
}
}
}