I used to play a game called Sentence Auction. Print up money from your home country and give each group of students the same ammount of money. I used to do $1000 in $10 and $20 bills. Then write a bunch of sentences on the board. Some will be correct, some will contain errors.
The beauty of the game is that you can work in what ever you want/are working on: grammer points, spelling, appropriate questions and answers, the list is endless. When it starts, you read out the sentences and get the groups to write them down and discuss whether or not they contain errors. Then the bidding begins. I used to act like an auctioneer with funny, fast talking. The groups bid on and buy the sentences. The team with the most correct sentences at the end is the winner. They get really into the auction and bidding part of it. Bids must be in English to be accepted.
Modify the rules and procedures for your group level and behavior expectations. I have had this take whole classes up and they want to do it again. The reveal is fun. When you identify whick were good and bad sentences, and why.Sentence Auction,