Some flash games don't work because they are running on ActionScript 3 which is unsupported and haven't been patched in by ruffle yet, be patient. If you want an app, I'll add it, if not it'll be added to a list of games that I'm waiting for.
The ones I've added and am waiting for support: Happy Wheels Demo, Happy Wheels, Vex 1 and 2.
If you want to add your own flash embeds to your websites, paste this code in, and replace the "SWF FILE URL" with the swf file url and switch the width of the application to one that works with your site. I use the default 620 because it matches my website. If you want to know more, here is a video from Sips.
<script src="https://xxsibxx.github.io/ruffleembedsetup112/ruffle/ruffle.js"></script>
<div class="swf"dir="ltr" style="text-align: left;" trbidi="on">
<embed height="480" pluginspage=" http://www.macromedia.com/go/getflashplayer" src="SWF FILE URL" type="application/x-shockwave-flash" width="620"></embed>
</div>