Everything is free to play. Supporting us doesn't unlock any problems or perks.
Kyoten is run by one person. Your support goes toward growing Kyoten: new problems and features, contests, running the servers, and more.
Support is handled by an outside service, OFUSE (in Japanese). No payment happens on this site. Because this goes to an individual, it is not tax-deductible.
Support on OFUSEFeedback and kind words help a lot too. Contact & feedback