Mostly for fun. Something kinda helped by that Haiku retains some interesting concepts (e.g. built to have small footprint, written in C++, object-oriented and

Mostly for fun. Something kinda helped by that Haiku retains some interesting concepts (e.g. built to have small footprint, written in C++, object-oriented and concept-oriented API, database-like filesystem, replicants, standard scripting mechanism, ...) and being enough different from other Unix-like systems.