LitRPG Books

What is LitRPG you ask?  It's a scifi or fantasy story that follows the two Commandments of LitRPG

1) A LITRPG SHALL involve some type of expliticitly stated progression (ie leveling, report of item finds, quests, etc)
2) A LITRPG SHALL involve a game-type world of some kind that the main character has been involved in