This is a repost from the main VB6 suggestions thread, which triggered an idea.
Is this idea to: A) make it easier to code things up, B) improve game mechanics consistency, or C) improve gameplay experience?
I suspect it's mostly A+B, with some C thrown in. In particular, it solves the problem of magically teleporting teams.
On the "A" front (with some "B" thrown in), it feels like you've identified more unit capabilities that can be handled using the same mechanism as e.g. anti-armor or anti-orbital (I haven't been playing close attention to the details of the ground combat stuff, so I probably got the names wrong). A nice thing about this is it allows for hybrid units with an intrinsic ground combat capability, e.g. a Xeno force that has both xeno capabilities and ground combat capabilities in case they dig up something nasty or pirates decide to raid them.
This hybrid ground unit idea leads me to suggest having an "Embassy" unit for diplomacy, which can be emplaced on an alien world (rather than just being in a ship in orbit) - the combat component would be the equivalent of the Marine guards at a US embassy. Note this is not intended to replace the diplomacy ship, rather it's an alternate mechanism analogous to orbital vs. ground terraformers.
The next coding/mechanics idea this leads to is that there seems to be a "ICommandable" abstraction; things that implement ICommandable can have a commander attached that applies bonuses. I can think of colonies, ships, research complexes, and military units as the existing ICommandables at this moment. One thing that stands out in this list is that a research complex is a facility, while a colony owns multiple facilities (multiple scientists working on different projects, factories, etc.). This seems like a little bit of an inconsistency in level of detail. So the questions here are "do you need to think some more about how leaders interact with the production capabilities of colonies (possibly by introducing "ministers" who are analogous to staff officers on ships)" and "Are there other things in Aurora that should implement ICommandable?".
Another question: "Are there other capabilities out there that ground units should be able to fulfill?" (which presumable would be boostable by commander abilities).
If one carried this reasoning to an extreme, factory complexes and research labs would be just another form of ground unit. I do NOT think this is a good idea, however - I think designing such installations would add to micro-management (and possibly code complexity) without a commensurate increase in gameplay, and would probably delay the Aurora release. It might be fruitful, however to think about facilities as "canned" ground units that have non-editable OOB and are very difficult to move. To a certain extent, this would bring things full circle back to PDCs, but with them being facilities (like a factory or research lab) that have anti-orbit capabilities rather then ships that are stuck on the ground (which is where I think the special-case-code problems came in with their first incarnation). As I said, I wasn't paying close attention, but it seems like there were some "doesn't quite fit" issues with anti-orbital static ground units that might be solved through the introduction of "fortification" facilities.
Taking this even further might lead to "terrain" abstractions for ground combat, where facilities have units explicitly defending them. The facilities would be clusterable (into cities) so that one unit could defend several facilities, but there would presumably be some efficiency penalty to encourage spreading them out to allow the possibility of defeat in detail (for example mineral deposit hotpoints that mines would be built on, and/or population hotpoints where people would want to live).
Note: none of the above is intended to say "I think you should do a major rewrite to xxx", instead it's just some ideas on tweaks you might want to make in the current mechanism to take you closer to your new idea and/or avoid painting yourself into a corner in the code if you want to go down one of these roads in the future.
On the "C" (gameplay) front: Overall, it seems a good solution to the instant teleportation problem, and from a fiction-driver side having a military component to a xeno site could lead to lots of richness (e.g. is the expedition commander scientific or military? This brings up the question though: "can scientists command a (military) ground unit?".)
My main concern is to not introduce overly-burdensome mechanics into more parts of the game (e.g. the original maintenance/refit rules). For example, it's probably not worth having a military component to an embassy, since whichever planet they're on should be able to overwhelm the military part easily. The way it would make sense would be by sneaking stealth-equipped spies in as part of the military unit, but that starts to get you back into worrying about special-case situations for the stealth capability (which maybe should simply be "intel") or if there was a "low-level threat" abstraction that endangered the diplomats that required a security element to reduce.
John