We developed a new weapon reverb effect for the purposes of increasing immersion, particularly during the Hyperborea chapter. In short, firearms now have different trail-off sounds in different kinds environments. Currently there are three environment presets: Indoor, outdoor and outdoor enclosed. It works by using a global reverb effect, which is set for the entire map in Hammer. Then, any areas which need different reverb effects can have a brush entity, called a func_reverbvolume, placed over them. Any relevant entity will then use the reverb volume's preset instead of the global one, as long as it is inside the volume.
The system supports the player, npcs, and explosions. And since the system is server-side, all entities use the correct reverb setting for their location, regardless of where the player is.
This will more than likely be in the initial Steam release of Missing Information (at least partially). The system itself is complete and all needed assets have been created, so the only thing that remains to be done is to implement it into the maps.
Currently we can't say when our next release will be out.