Really, it would be something what everybody use and need.

Modern times are different from the past, so you hardly could project old cases. Furs, cigarettes, bullets and even precious metals are not the things modern people will agree to take as a payment.

It could sound crazy, I know, but how about f.e. smartphone (ias physical object, device) as a black market currency? Negative PCR test result, some vaccination QR codes, even login credentials to some computer game.

Try to think in that direction, there could be many interesting ideas.

Really, it would be something what everybody use and need.

Modern times are different from the past, so you hardly could project old cases. Furs, cigarettes, bullets and even precious metals are not the things modern people will agree to take as a payment.

It could sound crazy, I know, but how about f.e. smartphone (ias physical object, device) as a black market currency?

Try to think in that direction, there could be many interesting ideas.