I, Robots the rpg

Had an idea this morning; post apocalyptic setting ala after humans have disappeared from the earth. Robots are carrying on their own civilization and the PCs are robots. Mysteries and unanswered questions abound related to what has happened in the past. No simple answers there, with multiple causes contributing to the fall of planet earth, and supposed death of humanity. Character classes are security/combat robots, maintenance/technitian robots, butler/protocol robots (butler and other servator robots have become the priest of the cult of the maker) could also be room for cybots with slightly corrupted programing and possibly emerging psionic powers. Call it Gama World meets Walle.