Command & Conquer (RA2 Yuri's Revenge or Generals style play) + FPS where I start the game in RTS mode and at any time I can click and "assume" a unit on the ground where I'm dropped into an FPS version of the map I was just viewing. If I die, I resume the commander role. Or if at any time I want to command again, AI takes the unit back over and it either stops or resumes doing whatever it was doing before.

I guess Renegade might be what FPS looks like, but I'm unaware of a game that combines both.