Here's some ideas that I've come up with to solve a few problems:
A new player comes in and plays. After x amount of moves, they get a one-time bonus in their treasure chest of some doubloons, let's say 5 Silver Doubloons.
At the same time, if they were referred by someone, their referrer would
also receive a one-time bonus, let's say 1 Silver Doubloon.
At the end of the month, when referral gold is calculated, the recurring monthly bonus per referral would be higher than it is now...let's say 5 times more -- 2500 gold instead of 500 gold.
I think this would not only encourage more people to refer others, but it would also give new players an idea about what doubloons can do and what they could earn by referring others.
This way, if you refer 100 people and 50 of them manage to get past the x amount of moves that it would take, then you could earn 50 Silver Doubloons. At the end of that month you would earn 125000 referral gold. If all 50 continued playing, then you would earn 125000 each month thereafter. Obviously the numbers may change a little but the principle is the same.
Of course, there's a potential for abuse, but that's something that we can keep an eye on.