I don't think any paradigm is inherently better at managing complex and messy state. I've worked on several very complicated applications written in a pure FP s

I don't think any paradigm is inherently better at managing complex and messy state. I've worked on several very complicated applications written in a pure FP style which handled complex, shared mutable state really elegantly (and many OO applications where state management was a terrible mess...). And more generally I think that pure FP and specifically effect-oriented pure FP gives you really nice, composable tools to handle complex state safely in concurrent applications. But yeah, for game development pure FP is probably a bad fit because you need pretty precise control over memory allocation and layout (from what I understand, never actually done any game dev).