no pressure
mmmm i have never eaten roo and my longstanding aversion to the meat of the bovine and marsupial might be a handicap. that said, I cook a great steak
An egg to bind is mandatory, yep. It helps to have some cooked rice, breadcrumbs, or potato as well to help the burgers keep their shape. Breadcrumbs are the easiest to add but if you are avoiding wheat, maybe rice is better.
I'd add some minced up onion/garlic, season with salt and maybe some spices and/or fresh herbs. Parsley, coriander, rosemary all go with roo. I think oregano would also go with it as it's a gamey meat.
hope that helps