diff --git a/src/minesweeper.js b/src/minesweeper.js
index 64c4c6a..02f586d 100644
--- a/src/minesweeper.js
+++ b/src/minesweeper.js
@@ -6,10 +6,10 @@ import {
 } from './modules';
 import { levels } from './levels.js';
 
+const TEST_MODE = true; // set to true if you want to test the game with visual hints and separate leaderboard
 const VERSION = "0.3.12";
 const MOBILE_BUSY_DELAY = 250;
 const PC_BUSY_DELAY = 500;
-const TEST_MODE = false;
 const CASUAL_MODE = false;
 
 export const Minesweeper = function(appId) {
diff --git a/src/modules/database/db.js b/src/modules/database/db.js
index 783c88a..ad760f0 100644
--- a/src/modules/database/db.js
+++ b/src/modules/database/db.js
@@ -3,6 +3,9 @@ import 'firebase/firestore';
 
 export class DatabaseService {
     constructor() {
+        // keys to interact with firebase
+        // not a secret: https://stackoverflow.com/questions/37482366/is-it-safe-to-expose-firebase-apikey-to-the-public/37484053#37484053
+        // but better moved to an environment variable
         const config = {
             apiKey: "AIzaSyAbDzNHCSFh59e3r5sZA4_2ZHJnJ6SCCxM",
             authDomain: "moment-188701.firebaseapp.com",