EBay

That's right. Your eyes aren't deceiving you. It is the same eBay you're thinking about.

How could a simple apocalypse affect the great capitalist pursuit? Even if humankind becomes extinct, eBay existence remain strong. It reincarnated into multiple red plastic letters which are distributed throughout the worlds. Any posthuman who holds a letter is an automatic user of eBay and can make various transactions through their plastic letter.

Instructions: When a letter is first activated, an identification number would be generated. Even if the user changes, the ID number would not change. All users will use their ID to complete their business transactions.

When a user holds the letter in his/her palm, the information generated by the letter would enter the user's brain via bioelectricity and an e-commerce interface would appear in the user's mind (let's just leave the exact technological explanation ambiguous). A user can sell items, browse and search for information about other users' products and purchase requirements.

How can a buyer get the item he/she buys? It's an unsolvable mystery.

Using some unknown criteria, the "forget-it-you'll-never-get-it" items listed on eBay are all grayed out. Naturally, these items cannot be purchased by the buyer.

For the tradable items, users have two options. The first option is "Local World Transaction". This option can only be used when both users are in the same world. The second option is "Pay a delivery fee to eBay". After the delivery fee is paid, your item would appear out of the air with a "pop" or out of nowhere. Don't ask me how it is delivered. This is our trade secret. This also applies to any sale of items.