It is the position of opengameart.org that minting and sale of Non Fungible Tokens (NFTs) from media under any licensing structure* which provides for use of such media free of cost implicitly attributes value to the uniqueness of the image and the exclusivity of its use. Common understanding of NFTs suggests to purchasers they are receiving something valuable for its scarcity and unique characteristics, in part granted by the nature of its association with blockchain technology. Because our game art is specifically open, e.g., NOT scarce, we feel this could constitute misrepresentation for pecuniary gain, Fraud--in both a criminal and a civil context, or any of the analogs of Fraud in most jurisdictions. 

Further, we consider it a violation of the rules of this site to mint an NFT of another's artwork. Doing so with the media from this site is de facto licensing of the artwork to another under different terms. See the FAQ question Can I still sell art that I've contributed to OpenGameArt.org? "[Other persons] do not . . . have the right to license your work to third parties under different terms."

*such as Creative Commons and other similar licensing instruments