To my horror I've just discovered that there is already a game called Erebus, I thought I'd checked pretty thoroughly before deciding on the name but obviously not.....
The other Erebus is an RPG for mobile which might explain why I missed it the first time around as I may only have checked Steam for any games with the same name, anyhow this leaves me with a bit of a dilema, so I'm considering changing the name to Operation Erebus hopefully this will avoid any confusion/law suits.