Just a few things that I thought about, when thinking about little things that Tremulous had that made it different from other games. I know this is going to be far different from Tremulous, but its worth taking some things into account. These are basic little worries that I thought I'd bring up. Feel free to blow them out the water!
Voices: The human voices in Tremulous had a very cool, gruff, action hero kind of voice. You imagine this gruff man with a smoke between his teeth gunning down wave after wave of aliens. A taunting ring in his voice as he shouts "COME ON".
This is good, its entertaining. One problem I found with Natural Selection 2, for instance, is the marines have very generic voices, too basic "future army" stuff. It got old fast and sounded mostly the same. There were no interesting lines nor voices. Murnatan humans should be instantly recognisable with their voice. They should be remembered.
Movement: Now, this is just basic but.. please don't make humans too slow. Keep the quake-dodging speed bunny hopping kind of feel? Though, by the sounds of it, you have that handled.
Finally, weapon design: The weapons and world of Tremulous was pretty "different". It wasn't all gun-metal grey and dark and opposing like, say, the world of natural selection. While it
did have a lot of grey, it was its own style. The thing I worry about is the weapons from this becoming too generic as well. Sci-fi is good and all, but theres a
lot of sci-fi games out at the moment. Try not to have generic Sci-Fi-ish stuff.
Edit: Building off of the weapon design. Please, please, please keep the absolutely badass hulking kind of ogre look to the battle suit. Dont make it all boxy or something. The old tremulous battlesuit was
intimidating!