One of the worst parts CurseForge's rule list is the broad nature of some of its requirements, which will likely create a slippery slope of banning content for vague or mundane reasons. On the tamer side, a lot of custom content centers around bringing brand-name products into the game like Gucci clothing and IKEA furniture.
The game is all about players creating a customized experience, including through modding, and many utilize things like the Sims 4 Extreme Violence mod, the infamous NSFW Wicked Whims, and the Basemental Drugs mod to introduce more chaos and fun into the title - all of which go against these rules in some way. Unfortunately for Sims 4 players, these guidelines exclude many fan-favorite mods and custom content.
