Naughty Dog used an internally developed programming language for the whole game (or at least most of it.) A big part of the appeal was apparently the dynamic nature of Lisps, which allowed reloading of code at runtime to simplify debugging. This article is a postmortem about Jak and Daxter; the next page also mentions the drawbacks of using GOAL, as well:

http://www.gamasutra.com/view/feature/2985/postmortem_naught...