For first-person modes in other shooters, and perhaps worth mentioning other combat-based games like Bushido Blade?
The first form of the genre. Mostly defined by non-polygonal graphics, and lacking of a ability to look up and down. Duke Nukem 3D is on the cusp of the classification, Quake aint, despite its similar gameplay structure.
The first-person perspective is not uncommon in Japanese videogames, but the first-person shooter is a rare enough occurrence that each is a curiosity.