The Marine Corps Information Operations Center (MCIOC) periodically conducts an Information Warfighter Exercise (IWX). MCIOC asked RAND to help develop a structured wargame for IWX with a formal adjudication process. The first edition of the IWX Wargame rulebook was published in 2021; this second edition provides the latest, updated and expanded, version of the game. The IWX wargame is an opposed event in which two teams of players compete in and through the information environment to better support their respective sides in a notional scenario. Teams represent an information operational planning team or its adversary force equivalent. During the game, each team generates a plan for information activities, and players are then called on to add details to their plan, amend that plan dynamically in response to in-game events, prepare discrete game actions as part of plan execution, and make cogent arguments in favor of their team's actions and against the actions of the opposed team. A panel of expert judges uses a structured process and a random element (dice) to adjudicate the success or failure of actions drawn from the players' plans. This second edition of the IWX Wargame rulebook includes material that was previously published as a supplement to the first edition rulebook: rules and considerations for conducting the IWX wargame (1) at the operational, rather than tactical, level and (2) with scenarios that focus on competition rather than conflict. Handouts and aids for playing the game, as well a brief Player's Guide, are also available for download.