This isn't a playable mod - it's a tool for HPL2 modders and custom story creators, for ATDD version 1.5 and later.
HPL2 Helper Scripts by Aetheric Games is a package of .hps files containing script classes and functions for ATDD version 1.5 and later. This is version 1.0. Extensive details, instructions and example code can be found on the FG forum.