The British Council's Learn English website offers 69 interactive activities for learning the rules of grammar. The activities are not listed by level so you will have to preview them to determine which activities are best suited for your learners.

Take a look / have a play at http://www.learnenglish.org.uk/grammar/archive/grammar_games_index_page01.html.

Note:- the games didn't work well when I used Firefox but were fine in IE7