If we talk game engines in particular, there is certainly no need for all the excessive functionality the Boost libraries provide.
However, there are surprisingly many parts of it, which I've seen being reimplemented in the small and big game engines over and over again (and, frankly, implemented quite a few bits of functionality myself).
Such as: * smart pointers
* memory pool allocators
* lexical cast
* variant types
* program options
* property trees
* tokenizing
* threading wrappers
* signals
* serialization
* filesystem abstraction
Read more: gd reflections
However, there are surprisingly many parts of it, which I've seen being reimplemented in the small and big game engines over and over again (and, frankly, implemented quite a few bits of functionality myself).
Such as: * smart pointers
* memory pool allocators
* lexical cast
* variant types
* program options
* property trees
* tokenizing
* threading wrappers
* signals
* serialization
* filesystem abstraction
Read more: gd reflections