Awesome work man, really impressive!
Sigh. When I see this I realise I should really try and learn to make missions again in the EIB engine.
Unfortunately the mission flow is created with pure code compared to the visual Kismet module in BIA:HH, plus the problem with static models being far les modular in EIB and RTH30. Unless someone spends the time in creating modular (re-arrangeable) 3D models and import them into EIB there’s little you can reuse from the base game to create a new mission. in Hells Highway most of the building 3D art is separated and you can reuse and combine to your liking. Lastly making pathway nodes for the AI is very time consuming and less versatile compared to the nav mesh system in BIAHH