Use a big green flag overlay to start the VM if needed

src/components/stage/stage.css

@@ -89,7 +89,10 @@ to adjust for the border using a different method */
     padding-bottom: calc($stage-full-screen-stage-padding + $stage-full-screen-border-width);
 }
 
-.monitor-wrapper, .color-picker-wrapper, .frame-wrapper {
+.monitor-wrapper,
+.color-picker-wrapper,
+.frame-wrapper,
+.green-flag-overlay-wrapper {
     position: absolute;
     top: 0;
     left: 0;
@@ -138,6 +141,16 @@ to adjust for the border using a different method */
     animation-fill-mode: forwards; /* Leave at 0 opacity after animation */
 }
 
+.green-flag-overlay {
+    width: 100%;
+    height: 100%;
+    display: flex;
+    justify-content: center;
+    align-items: center;
+    pointer-events: all;
+    cursor: pointer;
+}
+
 @keyframes flash {
     0% { opacity: 1; }
     100% { opacity: 0; }

src/components/stage/stage.jsx

@@ -7,6 +7,7 @@ import DOMElementRenderer from '../../containers/dom-element-renderer.jsx';
 import Loupe from '../loupe/loupe.jsx';
 import MonitorList from '../../containers/monitor-list.jsx';
 import TargetHighlight from '../../containers/target-highlight.jsx';
+import GreenFlagOverlay from '../../containers/green-flag-overlay.jsx';
 import Question from '../../containers/question.jsx';
 import MicIndicator from '../mic-indicator/mic-indicator.jsx';
 import {STAGE_DISPLAY_SIZES} from '../../lib/layout-constants.js';
@@ -71,6 +72,11 @@ const StageComponent = props => {
                         stageWidth={stageDimensions.width}
                     />
                 </Box>
+                <Box className={styles.greenFlagOverlayWrapper}>
+                    <GreenFlagOverlay
+                        className={styles.greenFlagOverlay}
+                    />
+                </Box>
                 {isColorPicking && colorInfo ? (
                     <Box className={styles.colorPickerWrapper}>
                         <Loupe colorInfo={colorInfo} />

src/containers/green-flag-overlay.jsx

+import bindAll from 'lodash.bindall';
+import React from 'react';
+import PropTypes from 'prop-types';
+
+import {connect} from 'react-redux';
+import VM from 'scratch-vm';
+import greenFlag from '../components/green-flag/icon--green-flag.svg';
+
+class GreenFlagOverlay extends React.Component {
+    constructor (props) {
+        super(props);
+        bindAll(this, [
+            'handleClick'
+        ]);
+    }
+
+    handleClick () {
+        this.props.vm.start();
+        this.props.vm.greenFlag();
+    }
+
+    render () {
+        if (this.props.isStarted) return null;
+
+        return (
+            <div
+                className={this.props.className}
+                onClick={this.handleClick}
+            >
+                <img
+                    draggable={false}
+                    src={greenFlag}
+                />
+            </div>
+        );
+    }
+}
+
+GreenFlagOverlay.propTypes = {
+    className: PropTypes.string,
+    isStarted: PropTypes.bool,
+    vm: PropTypes.instanceOf(VM)
+};
+
+const mapStateToProps = state => ({
+    isStarted: state.scratchGui.vmStatus.started,
+    vm: state.scratchGui.vm
+});
+
+const mapDispatchToProps = () => ({});
+
+export default connect(
+    mapStateToProps,
+    mapDispatchToProps
+)(GreenFlagOverlay);