I know these guys exist:
https://bitquest.co/they host a minecraft server where the ingame currency, emeralds, can be cashed in for the equivalent value of 1 bit (100 satoshi). i checked their server out a long time ago for a few minutes, ill tell you the basics of what i saw:
upon entering, the server prompts you to link your MC username on that server to a xapo email address, and every time you 'cashed in,' the bits would be sent to your xapo account. from this you can safely assume they used xapo's api to integrate bitcoin. i didnt really check it out to the point where i could see if you could use bitcoin to buy in game currency or not, but if this is along the lines of what youre trying to do, try shooting the devs over there an email, see if theyre willing to help you out or point you in the right direction.
