I wonder what the development time for the FS1/FS2 engine is, as compared with the development of missions, campaigns, ships, etc. (and let's not forget studio time for Robert "Admiral Petrarch" Loggia
)
What is involved in the actual FS2.EXE? Here's what I can come up with, off the top of my head:
1. The 3d engine (rendering ships, weapons, stars, etc.)
1a. The collision detection stuff to determine if a weapon (or ship, or asteroid, etc.) has smacked a ship or it's shields.
1b. The HUD display.
2. The physics stuff to track where everything is, and how it's moving... also the turning times, max speeds, etc. of the various objects; handling damage to shields / hulls / subsystems, etc.
3. The AI stuff: how enemies and wingmates react to various events. This also would apply to aspect- and heat-tracking missles, I guess.
4. The parser(s) to read in the *.tbl files and make sense of them.
5. The mission engine to handle doing things that are supposed to happen -- ie interpreting the SEXP's
6. Network stuff and whatever else is required for MP missions
7. Everything else
7a. The in-game user interface -- handling input from the player (flying the ship, sending messages, using weapons)
7b. The "out-of-game" user interface -- briefings, selecting ships and loadout, etc. And the cool Vasudan cap-ship interface
7c. Sounds.
7d. Whatever else I forgot about.
My point (I do have one) is that most of these are not trivial, but neither are they insurmountable. It seems to me that a big chunk of the development by
was developing the missions and other stuff that we already have in a usable format -- all the *.tbl and *.pof files.
If you look at the "bugfix of the day" at freespace2.com (I think) most of the stuff is mission related... Of course this could be because most of these posts were late in the dev't cycle (and the engine, etc. were already complete), or also because much of the engine stuff was ported with little modification from FS1.
So even if
and/or interplay don't give up the souce, a determined bunch of developers could write it. BTW I am
not volunteering to do this myself 
, but would be happy to assist...
