You released a free app in a crowded market. You are going to need something exceptional to stand out.
Searching for "sudoku" in the Play store returns "at least 1000 results" for Android apps. Potential buyers are unlikely to discover yours on its merit alone even if it is the best in the field.
Review sites are unlikely to want to review "yet another sudoku app". Your 1000+ competitors are all asking for reviews as well. Unless you can offer a compelling narrative or give them an interesting reason to write about this app in particular you should not be surprised that there seems to be little interest.
Your app also requires significantly more permissions than some of the other most popular sudoku apps. I don't know if most users care but given a choice between several free sudoku apps that might make a difference.
Searching for "sudoku" in the Play store returns "at least 1000 results" for Android apps. Potential buyers are unlikely to discover yours on its merit alone even if it is the best in the field.
Review sites are unlikely to want to review "yet another sudoku app". Your 1000+ competitors are all asking for reviews as well. Unless you can offer a compelling narrative or give them an interesting reason to write about this app in particular you should not be surprised that there seems to be little interest.
Your app also requires significantly more permissions than some of the other most popular sudoku apps. I don't know if most users care but given a choice between several free sudoku apps that might make a difference.