Authenticity cannot be settled on a video call. In this category the usual problem is not an obviously fake item but a reproduction inside genuine packaging, which is a question you can ask about directly.
What to ask them to show
The label, straight on and filling the frame. Not at an angle, not in plastic.
The cartridge opened, if they are willing — and if they are not, that is a legitimate position for a sealed or boxed item and a reason to price it as unknown.
The disc surface, tilted under light.
It running. This is the request that matters most and the one a live show makes easy: ask them to power it on and load it while you watch.
The case, manual and inserts, photographed separately.
What a refusal means
"I cannot test it, I do not have the console" is honest and common, and it should move the price rather than end the conversation.
What is not honest is "it works fine" from a seller who cannot demonstrate it. Those are different sentences and only one of them is a claim.
For anything sealed, ask who sealed it. Resealing is a known problem in this category and an honest seller will tell you they cannot vouch for it.
What this page will not do
It will not describe label printing or the shape of a cartridge shell. Reproductions get better at exactly those details, and a buyer relying on a general description is the person those improvements are aimed at.
What protects you if you get it wrong
A reproduction sold as an original is not as described: returnable for 7 days whatever the store's policy, and reportable.
A disc that does not work is the same argument, which is why asking them to run it before you bid is worth more than any inspection of the artwork.
Questions people ask
Is a sealed game safer?
Not necessarily — it is less inspectable. A sealed item is a bet on the seal, so ask about its history.
Does a scratched disc still count as working?
Ask them to run it. "Plays fine" demonstrated is worth more than any description of the scratches.
What about region differences?
Ask which region, and ask to see it running if you need it to work on your console.
More: spotting a counterfeit before you bid, Metzee's position on counterfeits, reporting a seller, questions to ask before bidding on video games.