Dunno. My "Knock Knock Jokes" was certified before they released anything, but they haven't deigned to list it. I suspect because they consider it to "duplicate content" with their own, lame, Knock-Knock Joke feature. You should read my review and make sure you don't make the same mistakes that whoever made this High Low game made. Seriously. I said "fishwife". Even Alexa confirmed I said "fishwife". I'm not quite sure [i]why[/i] I said fishwife. But it seemed a reasonable unreasonable test. And the skill decided that I had said "you guess correctly". Bzzzzp.
Oh, I meant to mention in my review that the exact same phrase is used each time when the number game replies. If you are doing another revision of yours you would make it more engaging by varying the reply. "7 is too low", "7 is a good guess, but it's too look". "7. is too low", etc.
Sometimes when I tell Alexa you guess she said canot guess unidentified number then goes back to asking who should guess first. Also when ever I'm guess Alexa number and guess 18 she tells me please guess a number between 1-100.