I knew this was going to happen. I made up my mind a while back that I wasn't going to do the music for Captain Zero so I could focus on development and actually get the thing done! But I never seem to follow my own rules.
So I dove head first into composition using Acid Wave and a loosely curated, but vast museum of VST instruments, samples and effects that I've collected over the years.
There's a reason I'm doing it myself, though.
In the original Captain Zero --which was made about 10 years ago or so in Dark Basic --and featured as one of their example games in the first issue of TheGameCreators online monthly publication-- I tried something I hadn't really seen before as far as game music:
I made dancy techno music, which is very common in video games, but since as a genre, techno is primarily loop-based, I decided to have a loop for each enemy type mix into the overall background music. The common enemy fighters were a base loop, tougher fighters brought with them a synth lead. Weirder, more abstract but rhythmic noises were added for more exotic enemies and full dark sounding marches came in with larger enemy ships. In the background, always there is a melodic, ambient spacey pad kinda sound.
Now with the ability to add realistic sounding orchestral motifs, I really have a lot of choices for bringing on the mood.
I remember Serious Sam where you always knew when trouble was coming because of the music. Everything looks quiet, but oh crap there's that music again!
In her book Unheard Melodies by Claudia Gorbman, she describes narrative film music or "background music" as "non-diegetic." This means it's music that the audience can hear, but the characters can't. It's meant to be a way of conveying the feelings going on in the scene to the audience.
Film makers have done amazing things with varying levels of diegetic music. In comedy, a really dramatic, sad piano score might be playing, and as it swells two lovers stop their conversation and look indignantly over to a corner of the room where a piano player is actually playing it in the scene. The piano player says "Sorry..."
Or "On the Road Again" is playing in a movie as we see a truck moving down the freeway from high over head, then we cut to the inside of the cab and see the truck driver change the radio station to a different song or a news program --changing the music between non-diegetic music for the audience, to full diegetic where the people in the movie can hear and affect the music themselves--seamlessly traversing the 4th wall in terms of background music.
Serious Sam music has the suspension-of-disbelief problem of having the background music magically alert the player when otherwise unseen trouble is coming.
I wish I had that in real life. When my boss calls me to his office it would be handy if "Sweet Dreams are Made of These" came on or the music from the beginning of "The Shining" started just to give me a heads-up about what I was walking into. When I met my ex girlfriend, the shower scene murder music from Psycho could have really helped me out.
For Serious Sam I consider it's just the player having a "bad feeling about this." He "feels" the enemy's presence and impending combat. Works for me.
For my game, I don't mind if music helps the player artificially. Your scanner is pretty much the range of the playable area, so the music isn't going to be that much of a surprise. Maybe stealth ships that have a cloaking ability will turn off their music loop when they cloak... or not have one.