From their announcement:
I’m excited to announce that Hasslefree have just released the last few models from the initial range for the Delgon culture for Twilight. It is now possible to field a full Delgon expeditionary force that is at least the equal of the original two factions.
It seemed wrong to release all these models without giving you rules to try them out in the game, so you can now download complete rules for all the models for free from the Twilight website. The January update will let you try out the Delgon, as well as adding a few more options for the Devanu and the Empire.