Looks very similar to my American Gamefowl Bantam hens. I used to breed a sub-catagory of the breed called Blue Face Hatch and they produced hens that look alot like yours. They are BBR in coloration but have green legs (or slate less commonly). Brown Red OEG is also very possible, I would say based on the body shape and her stature she is a very lovely Mixed Breed Bantam with a large percent of that mix being a Game-Type chicken.
TIP: All game-type chickens ARE notorious for producing some very broody girls so I'd watch for that!