It's a reverse alphabet, or mirror cipher.

Here's what it actually says.

"Normally when Players are erased, they are, for all intents and purposes, gone. Kept around on some frequency, maybe, but less tangible or aware than even folktale ghosts.

Which, of course, means that having them conscious elsewhere is very much not normal Game protocol. Not exactly against the rules, but those running the Game wouldn't be pleased to find out. So, it's important to hide this from them, and to err on the side of caution when discussing anything that seems out of place."