I am not a Windows/application programmer and can't help much myself, but hereby suggest a Spring feature in the form of a winamp plugin (or standalone).

What this plugin/program would do, would be to communicate with Spring itself. Spring would measure the "level of action" going on in a game (amount of damage inflicted over time / kills in total or some other reasonable/working algorithm) and report this to the external software. The more action there is, the higher the song number on the loaded playlist would be selected.

What do you think?

Could be fun - I'd load Doom Metal music high up into the playlist and Smooth Jazz at the bottom...

What would be more awesome is if Spring had a smart sound system where it would lower the simultaneous sound and volume the most units there are of the same type. For example, nobody likes hearing 100 blades firing at once and it's painful to the ears if you have your volume set fairly high.

I mean, I can hardly hear Spring at game start and then if the game gets as late as around 30 minutes, I can hardly hear my music. Would be nice to keep the same volume all the way through...

For about the forty-billionth time: Spring can:

1. Play music.
2. Can handle lots of Units firing without much clipping.

There are music players for Spring. There are Spring games where the sound doesn't clip on a regular basis.