Games age in three separate ways, and only one of them is about how much they were played.
What actually destroys them
Disc rot, accelerated by heat and humidity. It shows as small marks or a hazy patch and it is not repairable.
Battery death in older cartridges. Save batteries have a life measured in years and it passes whether or not the cartridge is used.
Light, which fades box art and yellows pale plastic.
Pressure, which cracks thin cases at the hinge.
What to do instead
- Upright, discs in their cases, cases not jammed
- Out of direct light — box art fades faster than anything else here
- Inside wall, off the floor, silica in the box during the monsoon
- Cartridges in sleeves or bags, so labels are not rubbed
Batteries
For a console or accessory stored long term, take the batteries out. Alkaline cells leak over years and the leak destroys the contacts and sometimes the device. This is the single most common way a stored handheld becomes scrap.
Sealed games
Treat the seal as the fragile thing it is: no pressure on it, no tape near it, no sunlight, and nothing stacked on top.
What it costs
Almost nothing — shelf space out of the sun and the discipline to remove batteries.
Questions people ask
Can disc rot be reversed?
No. Storage is the only answer.
Should I replace a cartridge save battery?
It is a common repair, and if you have done it, say so when selling.
Is a loft acceptable?
No. Heat is the main enemy in this category.