Many registrars are offering priority preregistration of domains, but this includes a non-refundable fee of at least $100. So in order to secure rockstar.ninja, for example, you would need to perform priority registration at all registrars (Name.com, GoDaddy, etc.) which process .ninja domain names. I doubt being out hundreds to thousands of dollars in non-refundable fees would be worth it to secure all but the best domain name.