I think I chatted about the initial World of Goo dev diary at some long-forgotten point in the past, but now TIGSource has amassed the links from the finished product for people to look at and learn from.
This collection describes the game’s progress from its hideous first draft (with Family Guy placeholder graphics!) to the squishy, gloppy project that we all know and love today. It’s an excellent representation of just how awe-inducingly committed the devs were to this project: the amount of work and rework that went into the menu system alone was nothing short of crazy.
It’s a set of bite-sized reads that veer away from being too boring or technical, so have a read.