I'm trying to remember this game that is based on a steam game. It's a FPS where things only move when you move. I think someone just recently released a game similar to that on iOS but I forgot what it's called.
Doom RPG is like that, and also Wolfenstein. You can also check Vonneguts and Glory. You sure you are looking for a shooter? Coz there are fantasy adventure as well like Grimrock... And Grimrock is a port.