No need to get snotty about it. The Boards are manned by fellow members. Many of us actually have lives. (I don't, but I've been thinking about getting one. I hear they are all the thing with the cool kids.)
I don't know much about gaming keys, but I gather they are electronic/digital/ software? You can only sell that sort of thing through the Classified section if you are going to ship electronically.
Paypal will not cover shipments that cannot be proven to be delivered. That means you have no seller protection for these keys should your customer claim non-delivery.
And gamers have a high percentage of self-involved, entitled, testosterone poisoned twits, who take any opportunity to " win". Not all obviously, but a higher percentage than the general population.
Do what you will, but I would advise you to post the keys on Kijiji or Craigslist and get paid in cash. Don't take Paypal for this sort of item.
BTW, if you do sell the items, the payment will be held by PP in escrow for 21 days against your seller performance. Just so you know.