@unsoughtinkerer first of all good luck with your project. In blockchain all data always there old or new. I can't say anything about Game but I think there should be way. I am telling this because of this platform steemit - steemit itself upgraded so many times. Curation and author reward system changed so many times but it had no issue of affecting old reward system on new. Another thing exactly related to Game industry and reward system - I read the article that Microsft going to use blochain technolgy for their Xbox (specially in reward system). About handling dynamic reward structures, only the blockchain developer can help you with that. Thank you for reading my article and kind comments. Hope we will play your webgame soon.