Laurent
Why not use a simple iFrame?
Upload your exported html5 game somewhere first, then
You can put this code on your WordPress blog post, and edit just the URL
of the game:
<iframe src="http://www.siteaddress.com/foldername/index.html" height="400" width="800"></iframe>
Or did you intend to use something more complicated? Sorry if I'm not getting the purpose right.