Why are you so concerned about any moisture absorption of your electronics? Most electronics products state they can operate in environments with 70% humidity.
Keeping electronic parts from absorbing moisture is an issue where you are planing on performing soldering or reflow on the parts as the absorbed moisture will immediately vaporize and will likely damage the part. Hence parts that have been in storage for a while without desiccant used will be baked to remove moisture before being soldered to a board.
Unless you are planning on moving those SNES cartridges immediately between a warm high humidity location, e.g. stored in a bathroom next to a shower, to a heavily refrigerated location, e.g. right next to the AC vent, I doubt you would ever experience any condensation on them.