After reading around to try and find out what this was I came across several articles. Apparently the creators decided NOT to include blood in the game to ensure it got a teen rating (though how any war / killing game gets a teen rating is beyond me)
Nether the less, people out there in the big wide world have haX0red around and are releasing a modified pak6.pk3 file which rectifies this issue and returns the 3D shooter to its typical tomato ketchup episodic.
Whilst I am not at liberty to distribute files such as this, the specifications are
Pak6.pk3 - 10,849 bytes.
Does exactly what it says on the tin.