So what i could says , try to make an FPS with some originality , you can't surpass games like COD4 made by 200 professionnal people !
Fully seconded, tough I think CoD4 wasnt made by 200 people...

The only teams of this size I know are the internal studios of EA and Ubisoft, 200 poor chinese producing Splinter Cell 22 and stuff..

But I think Ill go for a mix between realistic and futuristic... Something in between Crysis and Gears Of War.