What are these Strange Pattern Yugioh Cards
They clearly say Yugioh cards...are they knockoffs?

Those are fake cards*, although from the image I see they use the actual names of existing, original cards, and even the correct effects (for example Hiro's Shadow Scout).
Further reading on counterfeit cards.
*I know they are fake because... experience. But just to point out some of the details:

The YuGiOh logo on the back of the card is clearly not the same as the original YuGiOh logo
The colors are off. Those monsters look red (like trap cards) and trap cards look more like the monster color
The displayed attack on the monster card mimics the one on OCG/Anime (displayed on the bottom right in its own box), whilst the text is English - a clear mix-up