during the last year I put a lot of effort into creating a bitcoin riddle website which is now up since a few weeks (bitcoinriddles.com).
This is a non-commercial project that I did for fun and hopefully it introduces some new people to bitcoin.
There are however a few things I'm struggling with, maybe some of you guys have some ideas on how to solve this:
1) The site should also be usable by people not familiar with bitcoin (would be nice to introduce some new people to bitcoin). When they solve a riddle they can choose between:
a) direct transfer to BTC address (for experienced users)
b) email from coinbase, in that case they need to create a coinbase account when receiving the email in order to get the bitcoin
-> I would very much like to get rid of the coinbase API. But so far I really did not find any other way of easily transfering some bitcoin to people that have no clue about bitcoin. (e.g. paper wallet via email would be very risky as I am sure people would not be able to correctly swipe the paper wallet. Also I cannot assume that people already have a bitcoin wallet at the time when they solved a riddle)
2) I am currently only rewarding the user that solves the riddle first (right now usually 10000 bits per riddle). I therefore have to make the riddles quite hard so they don't get solved too quickly. This is probably putting off some users. I would very much like to reward also other users even when they have not solved it first, e.g. first 10 solvers get some reward as well.
-> The problem there is however, how can I prevent a user from just creating 10 accounts and getting all the rewards? (This would be a kind of sybil problem
Thank you for any suggestions!