Necromancer Rising is a FPS RPG. It's really good, but it's not $.99. Worth the money though for sure.
Solomon's Keep and the aforementioned Fastar are great, but don't get Duke Nukem. The controls are awful to the point of being unplayable.
The Same Dev is almost to the beta stage of another FPRPG. It's titled Mission Europa, keep an eye out for it.