I was able to figure this out... I think I understand better when people say its a "rotating" XOR, as the key starts at the beginning and then starts over, or "rotates" over and over till the end of the data. When I decrypted my character name, I needed to include a few additional characters of the same key to properly decrypt the whole name. I think I'll make a YouTube video demonstrating how this works, as you're never going to get this to work if you don't understand how P99 is obfuscating the game stream. Watching a 5 minute video on how XOR works was really helpful (https://www.youtube.com/watch?v=xK_SqWG9w-Y). This guy has a very simple video on how XOR works in general.