There is most definitely a pattern wit Mega Arbel, I think of it as a turtle. There's a head, front "arms" back "arms" and the tail.
That's just how I picture it and keep it in pattern. They only fit one way, you can put a few pieces in wrong like, 3 or 4 pieces, then you realize you did it wrong and have to go back. I've done that a couple of times first starting out. But once your built out enough it goes pretty easy.
They are beefy pavers though, measure 3 1/8" thick, Even better when your cutting in the soldier course.
All I can say is, have fun. Wish I had some pictures for you to check out, but I don't have them on my laptop.