That’s a lot of REALLY great questions! I’ll try and address them as best I can. 1) my first suggestion is to use similar games as a reference for everything (a generic “catch all” answer but so very important) 2) the goal is for music to help immerse the player - if it sticks out too much or gets in the way of anything (i.e. SFX) it fails at its most basic job. 3) length can be approach a lot of different way but if you are just starting out, keep it SIMPLE. A single loop will do the trick. How long depends largely on the gameplay loop - if you expect someone to spend 1-2 minutes with a particular track, usually 30-45 seconds is sufficient. If it’s 5-7 minutes that means they’d hear the same loop 10-14 times! It gets repetitive (see #2…). 4) personally, for a game revolving around a stealth mechanic, I’d avoid any really strong melodies - ambient would probably work best here. 5) don’t worry too much about frequencies now BUT be careful not to use sounds that are too close to important sound effects. Audio is a powerful tool for delivering information to a player and if that isn’t clear, again, see number 2! Please feel free to post what you are working on here! Much easier to give productive feedback on a work in progress than in the abstract.