Complications offer a way to add variety to your Minecraft experience with conditional bonuses and penalties. They're meant to invite you to look at your environment and how you engage with it in new ways - for example, with the Aquatic complication you'll be much more comfortable underwater than on land, and if you're Nocturnal then it'll be easier to see at night than in the daytime.
The base mod currently features seven Complications: Aquatic, Photosynthetic, Nocturnal, Blazefury, Deepdweller, Hyperactive, and Shulky. You can activate as many or as few as you like, and more can easily be added with a supplemental datapack or a command - create your own circumstantial triggers with predicates, and have them activate any effects in the game when fulfilled. The mod does a lot of the work for you - once you're set up, adding an additional Complication takes only a single line of code! (Check out the example addon pack here to get started.)
Part of the ✨Comfy Improvements series. Inclusion in modpacks is encouraged.