Overall gameplay should apparantly be integrated -16 LKFS, how to measure?  
Using Half Life 2's Black Mesa East level as reference for now 😅  

Based off these reference values, futz the loudness values of everything else  
If you're making an actual game, will probably have to include reference values for things like gunfire/swords clanging/magic effects, vehicle sounds, dialogue, UI sounds  

Reference:  
Footsteps: -28 dB normalized RMS  
Ambient background audio: -48 dB normalized RMS  
Physics prop impact: -24 dB normalized RMS  
Physics prop scrape: -35 dB normalized RMS  

Futzed:  
Foliage rustling: -46 dB normalized RMS  
Music: -24 dB normalized RMS, at least for this demo specifically due to the demo's low audio in general