diff --git a/README.md b/README.md
index 363dc5a..e6d4800 100644
--- a/README.md
+++ b/README.md
@@ -39,6 +39,7 @@ Scrolling your mouse will speed up or slow down time.
 | d     | toggles debug mode (including FPS counter)          |
 | n     | toggles display of nodes                            |
 | l     | toggles display of lines                            |
+| ?     | toggles display of help modal                       |
 
 ### Tweaking
 
diff --git a/css/style.css b/css/style.css
index 64880ab..0dcc521 100644
--- a/css/style.css
+++ b/css/style.css
@@ -6,3 +6,17 @@
 html {
     overflow: hidden;
 }
+
+#help {
+  display: flex;
+  justify-content: center;
+  background-color: black;
+  color: white;
+  position: absolute;
+  top: 0;
+  left: 0;
+}
+
+#help table {
+  color: white;
+}
diff --git a/index.html b/index.html
index dc4de1a..8a6d671 100644
--- a/index.html
+++ b/index.html
@@ -16,6 +16,91 @@
     <body>
         <script src="https://cdnjs.cloudflare.com/ajax/libs/pixi.js/4.2.2/pixi.min.js"></script>
         <script src="js/proximity.js"></script>
+        <div id="help" style="display: none;">
+          <h2>Help</h2>
+          <table>
+            <tr>
+              <th>Interaction</th>
+              <th>Action</th>
+            </tr>
+            <tr>
+              <td>mouse hover</td>
+              <td>push points away from cursor</td>
+            </tr>
+            <tr>
+              <td>mouse/touch click and hold</td>
+              <td>attract points to cursor, then explode outwards</td>
+            </tr>
+            <tr>
+              <td>mouse wheel scroll down</td>
+              <td>slow down time</td>
+            </tr>
+            <tr>
+              <td>mouse wheel scroll up</td>
+              <td>speed up time</td>
+            </tr>
+            <tr>
+              <td>left</td>
+              <td>hold to restrict points to the left of the screen</td>
+            </tr>
+            <tr>
+              <td>right</td>
+              <td>hold to restrict points to the right of the screen</td>
+            </tr>
+            <tr>
+              <td>up</td>
+              <td>hold to restrict points to the top of the screen</td>
+            </tr>
+            <tr>
+              <td>down</td>
+              <td>hold to restrict points to the bottom of the screen</td>
+            </tr>
+            <tr>
+              <td>1</td>
+              <td>makes points move linearly</td>
+            </tr>
+            <tr>
+              <td>2</td>
+              <td>makes points meander</td>
+            </tr>
+            <tr>
+              <td>3</td>
+              <td>makes points snappy</td>
+            </tr>
+            <tr>
+              <td>4</td>
+              <td>makes points bouncy</td>
+            </tr>
+            <tr>
+              <td>5</td>
+              <td>makes points elastic</td>
+            </tr>
+            <tr>
+              <td>6</td>
+              <td>makes points overshoot</td>
+            </tr>
+            <tr>
+              <td>f</td>
+              <td>toggle FPS counter</td>
+            </tr>
+            <tr>
+              <td>d</td>
+              <td>toggles debug mode (including FPS counter)</td>
+            </tr>
+            <tr>
+              <td>n</td>
+              <td>toggles display of nodes</td>
+            </tr>
+            <tr>
+              <td>l</td>
+              <td>toggles display of lines</td>
+            </tr>
+            <tr>
+              <td>?</td>
+              <td>toggles this help modal</td>
+            </tr>
+          </table>
+        </div>
     </body>
 
     <!-- Google Analytics -->
diff --git a/js/proximity.js b/js/proximity.js
index 6111499..a79ae3d 100644
--- a/js/proximity.js
+++ b/js/proximity.js
@@ -761,7 +761,7 @@ document.addEventListener('mouseleave', function (e) {
 /* KEYBOARD EVENTS */
 
 window.addEventListener('keydown', function (e) {
-    var i;
+    var i, help;
     if (e.keyCode === 37) { // left
         pointShiftBiasX = -1;
     } else if (e.keyCode === 38) { // up
@@ -822,5 +822,12 @@ window.addEventListener('keydown', function (e) {
         }
     } else if (e.keyCode === 76) { // l
         drawLines = !drawLines;
+    } else if (e.keyCode === 191) { // ?
+        help = document.getElementById('help');
+        if (help.style.display === 'none') {
+            help.style.display = 'flex';
+        } else {
+            help.style.display = 'none';
+        }
     }
 });

Interaction	Action
mouse hover	push points away from cursor
mouse/touch click and hold	attract points to cursor, then explode outwards
mouse wheel scroll down	slow down time
mouse wheel scroll up	speed up time
left	hold to restrict points to the left of the screen
right	hold to restrict points to the right of the screen
up	hold to restrict points to the top of the screen
down	hold to restrict points to the bottom of the screen
1	makes points move linearly
2	makes points meander
3	makes points snappy
4	makes points bouncy
5	makes points elastic
6	makes points overshoot
f	toggle FPS counter
d	toggles debug mode (including FPS counter)
n	toggles display of nodes
l	toggles display of lines
?	toggles this help modal