Vocabulary Builder:

https://play.google.com/store/apps/details?id=com.magoosh.gre.quiz.vocabulary&hl=en

https://itunes.apple.com/us/app/gre-vocabulary-quiz-from-magoosh/id890252250?mt=8&ign-mpt=uo%3D8

Build your vocabulary with Magoosh’s free vocabulary game for your Android or iOS device. Quiz yourself every day to learn the 1200 most important words!