In the book "AI Game Programming Wisdom 2", Neil Wallace from Lionhead has an article where he describes the benefits of using a Hierarchical Task Network for planning tasks. However, the article is very short on any sort of implementation details, as were the academic articles that the article cited. I'm somewhat familiar with another project where a third party HTN planner(SHOP) was interfaced with Unreal Tournament, however, my question is, does anyone know if there exists any information about how to implement a simple HTN planner, especially in the context of a game environment?

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Yea, I am trying to develop my own HTN from the same book chapter. It is proving difficult as some of the details on critics and backtreacking have been left out so it has become a bit of a guessing game. Also most of the academic papers on HTNs leave out any form of implementation details.. :-(.

I understand the core concepts, its just it would be helpful to have some pseudocode showing how to implement some of the more tricky parts..