What about an engine like Stratagus?
It's open source and uses LUA++ for it's scripts.
From what I've seen, Stratagus probably wouldn't work very well for an OP2 remake. It's geared toward old games like Warcraft 2 (where you have simple tilesets, simple units, simple everything). I think we would need a lot of modifications for OP2 to work with it (for example, take morale. I haven't seen any game that has anything like morale in it).
Yes, it does use Lua for scripting but I have a couple gripes with that:
-- Slow; the generality of a scripting language isn't necessarily needed either. We could just code the logic in C or C++ and it would be a lot faster (and still easy to mod later)
-- Having text files on the hard drive makes it really easy for something to change the inner logic completely. This is great for custom modding and such, but it could potentially make it easier to cheat (i.e. if the main part of the OP2 logic is implemented in script, you could easily change that script to give yourself a slight advantage over the other players; and still have it work fine. For example, to make your pathfinding more accurate, etc).
Furthermore it just seems sort of 'unprofessional' to have text scripts just sitting on the hard drive. Then the core has to parse these each and every time the game is loaded.
-- Lua's syntax is kinda weird, I personally don't like it.
Scripting would be nice for some things like missions, and maybe plug-in AI routines or something. But the core of the game shouldn't be based on scripts.
I think it would be more worthwhile to just write a new game engine specifically tailored for OP2. It would be faster, lighter, and better.
As for the data files themselves, it would probably make more sense to use new formats for them. Some of them (especially the map/saved game format) have some real inefficiencies and could be greatly redone. (For example, there is a max of 1024 units and 2048 tiles at a time on a map).
@Trix: yes, we would need to write everything from scratch. If we had the source code available we wouldn't need to think about any of this at all
That brings in the possibility of some things not working *exactly* the same as they did in normal OP2 (we do want a 1:1 mirror right?)
We could eventually get there but that would require more study of the assembly in outpost2.exe.
As for corporate teams and such, remember we don't need to make new artwork or sounds for anything. All we would need to write is a replacement engine, and then convert the existing data to new formats.