Learning may be many things, but at the end of the day, learning is personal, something one does to one's self. Using games to engage students in their learning process makes learning more appealing and is definitely a great way to do revisions. Below are two suggestions which learners can use both in the classroom and for self-study.
Sugarcane is a free educational game, which allows you to create different kinds of games, from matching to categorizing to
ordering and spelling.
Games can be shared with learners with a link or by sending them an email. Here is an example of different games focusing on Classical Music Composers. Teachers too can share their games, see other games which have been already made and edit them according to their context.
Playbuzz is also free, features different kinds of games to make and offerstips on how best to create different kinds of games. Games can also be embedded - always a plus if you have a class blog.
Though not necessarily designed for educational purposes, Playbuzz can be used with learners provided the quizzes focus on their learning context.