#Genefunk, like several recentish cyberpunk-style games, posits a stable cryptocurrency as the basis of the economy. While from a flavour perspective, this is fine and dandy, it feels odd not to have any volatility associated with crypto.
So a quick and dirty hack (assuming DnD5E)
At the start of each day, you roll a Market die (D2) and a Value die (d66). If the Market die rolls 1, the market is down and you reduce the value of your crypto by d66%. If the Market die is 2 the market is up and increase the value of your crypto by d66%
If your PC wants to "play the market" the process is a little different. The Market die is still d2, but the Value die is now d100. When you play the market you make an Int Check vs DC20. If you succeed, assume the market is up and roll the Value die twice, choosing the best result. If you only get DC15. Roll market die once and value die twice choosing most advantageous result.
If you roll 5 or less, assume the market is down and roll value die twice choosing worst result to reduce your crypto.
Needless to say this is all just for funsies and I have no desire to inflict market volatility on my PCs hard earned bitcoin 