Using jQuery on client side you can trigger route with $.get() function
%= input_tag 'play', type=>'button', value=>'Play', onclick=>"$.get('/play')"
or
<input type="button" value="Play" onclick="$.get('/play');">
To use jQuery you have to add the following line into your template
<script src="//ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js">
</script>