For almost 20 years, Hearts of Iron has been a prominent franchise in the videogame genre known as “grand strategy.” In these games, players don’t command individual characters or armies, but whole nations or even civilizations. In Hearts of Iron, which is now up to its fourth iteration, players lead nations and navigate them through (often fictional) conflicts, alliances, economics crises, and intrigues before and after World War II, exploring alternative historical narratives. What’s more, Paradox Interactive, the developer of Hearts of Iron 4, designed the game in a way that allows gamers to create their own customized versions, often called “mods,” which take the game into radically different timelines. By one count, more than 20,000 mods are available for Hearts of Iron. These include some that fall into the category of “total conversion modifications”—mods that are so ambitious that they effectively create entirely new game systems. A notable example is The New Order: Last Days of Europe, a huge project that crowdsourced the efforts of hundreds of volunteer fans. Since its conception in 2014, …