This is the XF 2 version of Referral Contest.
If you are looking for a simpler referral system, check out my Referral System add-on.

Referral Contests allows you not only to create referral contests for your members, but you can also make your board invitation only.

Referral contests are optional and members can use their referral link without contests.
Integrates with DBTech Credits add-on.