The title on the box is a weak guide to price here. The state of what is in it is a strong one.
What moves the number
Completeness — sealed, complete in box, or loose. Three different markets.
Region, because a buyer whose console will not read it has no use for it.
Whether it works, demonstrated rather than claimed.
Condition of the case and manual, which for a complete game is part of the item.
Why two of the same differ
One seller booted it on camera and showed the spine. The other wrote "working". Thirty seconds of a game running is worth more than any sentence. Describing game condition.
How to find out rather than guess
Compare completed sales in the same state — complete against complete, loose against loose. Mixing them is the most common and most expensive error in this category.
For older cartridges, say whether the save battery still holds. It changes what a buyer is getting.
Consoles
A console is worth what it comes with: controllers, cables, power supply, memory card. Every missing piece is money the buyer has to spend before it works, and it comes off your price whether you say so or not.
Questions people ask
Is a sealed game worth a lot?
Sometimes, and a seal is not a certificate. Say what you know about where it came from.
Does a scratched disc still sell?
If it plays and you say so. Untested discs sell at untested prices.
What about a box of loose cartridges?
A lot, counted and described. Pull out anything sought-after.
More: pricing games, packing games.