ZDoom

Thanks so much
You should make a thread for this in graphics/audio patches or something so it isn't lost in the closed feature suggestions.
Can't wait for the next GZDoom update to be able to use it, I'm excited.

Here's a quick and simple zscript mod that randomises the colour of the Dead & Gibbed Marine sprites. Took a whole five minutes to make, so here you go

If you want a reference, this was used in ZDCMP2. Mostly visible at the dig site, and in the flowing river of corpses you can glimpse through cracks in the rock wall of the tunnel leading to it.

Though since this was done before the [wiki]TRNSLATE[/wiki] lump and before [wiki]ZScript[/wiki], one could make a much nicer implementation now!
(It's map script #38 to create the translations, and actors/props/marinecorpses.txt for the actor code, with one fugly bunch of chained A_JumpIf because DECORATE didn't want to use Thing_SetTranslation(0, 10+args[0])...)

Neato

You do not even need an engine feature for it.
What you need is to define different dead marine sprites with varying translations being set and then a random spawner choosing between them. Load that as an add-on mod and you're done!

I saw this on a different source port
Each dead marine or gibbed marine had different colors, red, green, grey, brown, etc.
Just wondered if that could be added to GZDoom