The point of the thread is “specific things that can be done quickly and without significant code reworking”, IIRC.
I know the fuel truck can be done with existing resources: take the flatbed chassis and add a lot of the External Tanks on the back.
Medical-grade bionics could be implemented but the difficult part is working out what they’d be, whether the player would want to install them and why, etc. Needs its own thread, but is achievable.
1x1 buildings can be easily accommodated in JSON. John Candlebury’s pretty good at those. Muti-tile buildings require fiddling around with the mapgen code. In any event, I’ve got a thread up for standardizing map colors and getting a legend together so people can have a shared expectation for a brown < means: we’d need to get that sorted at the same time.
Telephone poles may or may not make sense lore-wise (more economical, long-term, to bury the wires) but they’re likely straightforward in terms of coding. Solar-powered LEDs might justify street lights, but that’s its own thread.
Underground hostiles are their own thread. I agree that we need more, but in order to make underground bases worthwhile the player needs to be able to make “safe” or at least “spawn-unlikely” areas. Same problem as with taking over a Mansion: it’s so large that critters will spawn inside it, so you have to wall off areas you’re not constantly using.
Hoping that helps.
