You're going after the wrong target market. Sudoku apps are for middle aged women (Yes, I generalize, but it's pretty much the only game my mother plays on her Android phone).

Stop targeting your ads at Android related users (Android forums, games review sites). Go find a place where the people who will actually play your game hang out and then advertise there. Mothers group forums, parenting forums, business traveler hangouts, school teachers - whatever.