Yeah, HTML5 isn't optimal for SEO even though search engines can crawl them now. But I really don't need SEO for this type of site as I don't sell anything or need customers on the site itself. It is just a place for users to go after they have played one of my games and want to see what the studio is up to
And if you google "frozen dev" for example my website should appear high enough anyway and that is all that matters for a studio website