I found the two beat-the-average games, Kingdom Rush and Knights of Pen and Paper, to be very enjoyable. Kingdom Rush offers a deep and well-designed tower defense experience on both Android and PC. Knights of Pen and Paper is an even deeper game, but not too intimidating, especially if you are familiar with other turn-based RPGs. Either game, on its own, I would recommend beating the average for, so beating the average for both makes perfect sense.