If anybody in interested to mine in an invite-only blockchain project, check out Merit (
https://www.merit.me/). You'll need an invite link to get in. I have put in my invite link below.
Mining rewards are of 2 types:
1) Rewards from Mining - both CPU and GPU mining available; GPU's obviously give higher rewards. AMD mining not available at the moment, though.
2) Rewards from growing your network by inviting others (like I am doing now

)
I'm excited for the project primarily because I can invite my non-crypto friends over to the Merit blockchain with just a web link over email/SMS. And I can send Merits to aliases (Eg. @elonmusk) instead of alphanumeric addresses. It's easy to get someone started.
Check out this sweet feature by Techcrunch -
https://techcrunch.com/2018/05/09/a-modcloth-cofounder-just-launched-an-invite-only-cryptocurrency/You can use my link to get a taste of Merit. Would appreciate a PM on Telegram (@abhijoysarkar) so that I can accept you quickly (all invites need to be approved for the invitee to be accepted into the blockchain).
My invite link: https://wallet.merit.me/?invite=SarkarAbhijoy