Man, I always wanted to play Chaosium's Call of Cthulhu, but never got a chance. I have heard of Nephilim, but only in passing.

As for the similarities, I think that was the plan. The writer of those 3 supplements loved the horror genre, as well as the "things man weren't meant to know" stuff. His idea was directly inspired by TSR's Alternity setting, Dark*Matter (which was a great setting in my opinion).

I an sorry you don't roleplay anymore. I find its a great social event and has expanded my general knowledge immensely throughout the years.