A very neat idea and juice galore!
More sound impact from hitting enemies is the only thing lacking from giving the juice that extra bit of punch (and a slightly toned down screen shake)
I found myself almost always using the shotgun because it was the only thing which reliably and quickly actually killed enemies. Some more incentives to use other weapons other than running out of ammo would be nice (significantly faster rate of machine gun fire, more accurate plasma gun etc). For a linear and closed game level like this one, detours to find buttons were quite annoying. Maybe rewarding the player with ammo and health for taking a exploratory risk would be better .
Still really well done! Wish you guys the best if you decide to expand on this or make more stuff like this in the future!