I'll keep these things in mind.
I've already got some ideas that might work, I'll just need a little time to record, track, and upload them.
I like the "recurring theme" and "action" ideas, I believe I can work off of that.
Part of what takes time is the fact that although a musician can dream up a musical idea that they think sounds great, often when it is actually implemented the final product plays back very different than how they imagined it. I know, I've written music on computers for over 20 years, since before many of the DAWs that exist like they do today started coming into the hands of the personal home computer user. In the last several years the technology has really taken off!
EDIT: Regarding customizing the playback for the odds of winning/losing, what would really be cool would be music that dynamically changed each phrase* according to how the fight went on, although I'd imagine it might be a headache for the coders. What could be an easier compromise would be a little victory tune if the player wins, or losing tune if not, right before going back to the main geoscape view zooming out. Personally, I'd rather concentrate on getting some basic tunes for combat that work, first, before adding complications.