a user who possessed any specific item held only the right to use that item within the game. If the user became unable to access the item, or if the game account was hacked and the item was taken by another user, it was difficult to resolve the problem without the intervention of the game company even if the user claimed his/her digital ownership. Moreover, all copyrights of these items belonged to the company that developed and serviced the games. However, such risk is relatively lower in NFT-based games. As they are open source, anyone can verify digital ownership of game items. The risk of loss or hacking is low and digital ownership of such items is wholly retained by that user. Yet, it does not mean that NFT-based games only have positives. Innumerable NFT-based games have appeared with the growth of the blockchain market, among which some games are money-grabs, and in worst cases, some games involve scams. Due to these games, NFT games can present critical risks for both players and investors.