It would probably be a good idea to offer escrow as you are very new here and it would not be advisable for people to join without any kind of guarantee of receipt of payment.
Don't worry, I got his back. It's my site he's advertising. I'll make it more formal if you really want one.
IMO this should be more prominent in the OP as people will assume that it is just a newbie and will be reluctant to join, however I think you confirming that you are a part owner should be sufficient.
edit: your game looks really fun, I will have to play around with it in more details tomorrow evening.