diff -ruN orig/css/quizzity.less mod/css/quizzity.less
--- orig/css/quizzity.less
+++ mod/css/quizzity.less
@@ -1,4 +1,9 @@
-@import (css) url(https://fonts.googleapis.com/css?family=Roboto+Condensed:400,700);
+@font-face {
+    font-family: 'Roboto Condensed';
+    font-weight: 400 700;
+    font-style: normal;
+    src: url(../fonts/RobotoCondensed.ttf) format('truetype');
+}
 
 @water: #4576b2;
 
@@ -152,7 +157,7 @@
 }
 
 // Source code panel
-#github, #paypal {
+#github {
     .box(3px, 0.9);
     bottom: @pageMargin;
     left: @pageMargin;
@@ -161,19 +166,9 @@
     padding-left: 10px;
     padding-right: 10px;
 
-    font-size: 20px;
+    font-size: 14px;
 
     .transparent;
-
-    a {
-        text-decoration: none;
-        color: black;
-        pointer-events: auto;
-    }
-}
-
-#paypal {
-    bottom: @pageMargin + 40px;
 }
 
 // flashing score during the game
@@ -287,10 +282,6 @@
         display: none;
     }
 
-    #paypal {
-        display: none;
-    }
-
     #points {
         top: 45px;
     }
diff -ruN orig/index.html mod/index.html
--- orig/index.html
+++ mod/index.html
@@ -4,24 +4,12 @@
         <meta charset="utf-8" />
         <title>quizzity - a geography game</title>
         <meta name="author" content="David Peter">
+        <meta http-equiv="Content-Security-Policy" content="default-src 'self'; img-src 'self' data: blob:; style-src 'self' 'unsafe-inline'; font-src 'self'; connect-src 'self'; frame-src 'none'; object-src 'none'">
         <meta name="viewport" content="width=device-width, initial-scale=1.0">
         <meta name="description" content="quizzity is a geographical quiz where you have to guess the location of several cities on a world map while receiving points for being both accurate and fast.">
         <meta name="keywords" content="quiz, game, geography, cities, capitals, world, map, teaching, learning, educational, open source">
 
-        <meta property="og:type" content="website">
-        <meta property="og:image" content="https://david-peter.de/quizzity/icon/quizzity.png">
-        <meta property="og:title" content="quizzity - a geography game">
-        <meta property="og:url" content="https://david-peter.de/quizzity/">
-        <meta property="og:description" content="quizzity is a geographical quiz where you have to guess the location of several cities on a world map while receiving points for being both accurate and fast.">
 
-        <meta name="twitter:card" content="summary_large_image" />
-        <meta name="twitter:site" content="@sharkdp86">
-        <meta name="twitter:title" content="quizzity - a geography game" />
-        <meta name="twitter:description" content="quizzity is a geographical quiz where you have to guess the location of several cities on a world map while receiving points for being both accurate and fast." />
-        <meta name="twitter:image:src" content="https://david-peter.de/quizzity/icon/quizzity.png" />
-        <meta name="twitter:image:width" content="800" />
-        <meta name="twitter:image:height" content="420" />
-        <meta name="twitter:url" content="https://david-peter.de/quizzity/" />
 
         <link rel="icon" type="image/png" href="icon/quizzity-196.png" sizes="196x196">
         <link rel="icon" type="image/png" href="icon/quizzity-32.png" sizes="32x32">
@@ -49,8 +37,7 @@
             </p>
         </div>
         <div id="points"></div>
-        <div id="github"><a target="_blank" href="https://github.com/sharkdp/quizzity"><i class="fa fa-github"></i> Source on GitHub</a></div>
-        <div id="paypal"><a target="_blank" href="https://paypal.me/sharkfishsoftware"><i class="fa fa-paypal"></i> Support this game</a></div>
+        <div id="github">Map: Natural Earth (public domain). Cities: GeoNames, CC BY 4.0.</div>
 
         <script src="assets/jquery/dist/jquery.min.js"></script>
         <script src="assets/leaflet/dist/leaflet.js"></script>
@@ -58,14 +45,5 @@
         <script src="assets/leaflet.awesome-markers/dist/leaflet.awesome-markers.min.js"></script>
         <script src="assets/leaflet.geodesic/dist/leaflet.geodesic.umd.min.js"></script>
         <script src="js/quizzity.js"></script>
-        <script>
-            (function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){
-                (i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),
-                m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
-            })(window,document,'script','//www.google-analytics.com/analytics.js','ga');
-
-            ga('create', 'UA-39945208-2', 'david-peter.de');
-            ga('send', 'pageview');
-        </script>
     </body>
 </html>
diff -ruN orig/js/quizzity.js mod/js/quizzity.js
--- orig/js/quizzity.js
+++ mod/js/quizzity.js
@@ -23,7 +23,8 @@
             maxZoom: Quizzity.maxZoom,
             minZoom: Quizzity.minZoom,
             noWrap: true,
-            tms: true
+            tms: true,
+            attribution: 'Natural Earth; GeoNames (CC BY 4.0)'
         }
     ).addTo(this.map);
 
@@ -88,7 +89,6 @@
     this.$panel.show();
     this.$panel.startAnimation('bounceIn');
 
-    ga('send', 'event', 'button', 'click', 'start-game');
 };
 
 Quizzity.prototype.showPoints = function() {
@@ -152,11 +152,6 @@
     this.$dialog.show();
     this.$dialog.startAnimation('zoomIn');
 
-    $.ajax({
-        type: 'POST',
-        url: 'php/log.php',
-        data: { guesses: JSON.stringify(this.cities) }
-    });
 };
 
 Quizzity.prototype.isGameActive = function() {
@@ -204,7 +199,6 @@
         content += '<tr><td>Time:</td><td>' + (Math.round(city.time / 100) / 10).toString() + 's</td></tr>';
         content += '<tr><td>Points:</td><td>' + city.points.toString() + '</td></tr>';
         content += '</table>';
-        content += '<a target="_blank" href="http://en.wikipedia.org/wiki/' + encodeURIComponent(city.fullName) + '"><i class="fa fa-external-link"></i> City information</a>';
         content += '</div>';
         cityMarker.bindPopup(content, {closeButton: false});