Kahoot! is a classroom response system which creates an engaging learning space, through a game-based digital pedagogy. Kahoot!
Have you tried Socrative and Moodle Real Time quizzes for whole class quiz activities and/or revision sessions?
If so, then you might want to give Kahoot a go: Its quiz tool allows
Multiple choice questionsUpload (by dragging) images from your own computerAllows video questions (via YouTube) which you can top and tailTop 5 Students appear on leaderboard after each questionTeacher controlTeacher can download results as a spreadtableWorks on any platform, PC, notebook, smartphone, ipad etc
Other than the quiz tool you can also:
Create discussionsCarry out surveys
There is also a blog which has tutorials and comments from teachers - http://blog.getkahoot.com/
The designer of Kahoot is on twitter as @jamiebrooker and is amazing at returning your queries.