Роман1479,
<!DOCTYPE html>
<html>
<head>
<title>Untitled</title>
<meta charset="utf-8">
<style type="text/css">
#etsa {
width: 50px;
height: 50px;
background: url(http://us.123rf.com/400wm/400/400/speedfighter/speedfighter1001/speedfighter100100101/6236656-sniper-rifle-target-cross-hairs-silhouetted-on-white-background.jpg) no-repeat;
background-size: 50px 50px;
margin: -25px 0 0 -25px;
position: absolute;
transition: top 0.5s, left 0.5s;
-webkit-transition: top 0.5s, left 0.5s;
}
body {
margin: 0;
overflow: hidden;
}
</style>
</head>
<body>
<div class="block" id="block">
<div id="etsa"></div>
</div>
<script>
var el = document.getElementById('etsa'), timer;
document.onmousemove = function(e) {
window.clearTimeout(timer);
el.style.backgroundImage = ""
el.innerHTML = "";
var X = 0;
var Y = 0;
X = e.clientX;
Y = e.clientY;
el.style.left = X + 'px';
el.style.top = Y + 'px';
timer = window.setTimeout(function() {
el.innerHTML = "boom!!!";
el.style.backgroundImage = "none"
}, 500)
};
</script>
</body>
</html>