Hi,
I guess this was suggested before but one thing that really kills the immersion is the following:
The packs/clumps of enemies. I do like the idea of enemies coming in packs but the pack size and frequency throughout the map is just too predictable.
I can almost blind-shoot in the next corner knowing where an enemy pack will be. This leads to a really brain-dead running through the maps which feels kind of repetitive. Would be great if we had some more diversity in terms of enemy distribution on each map.