I learned about this game at a Pippin's math conference which I blogged about here. It's sad that that was almost a year ago and I'm just now using it. You can use a regular review worksheet or my personal favorite, a Powerpoint of review problems.
Students are in teams. You create a sheet with balloons on it and a place to write a team name. Or you can steal mine. Print this on paper and stick it in side of a page protector. Students write their name on it with dry erase marker.
Show a problem. Each team works it, which means every person works it. They agree on a team answer. Now reveal the correct answer. Whichever team(s) gets the correct answer gets to pop another team's balloon by using the dry erase marker to draw an X on it. If a team's balloons all get popped, then they can erase a popped balloon instead of popping someone else's balloon. But that's only an option after all of their balloons have been popped. Whichever team has the most unpopped balloons left at then end, wins.
My students loved this. The fun thing is to watch different teams try to form alliances and get other teams out. My students said it was like playing survivor because you never knew which teams were working together. Students were surprised by how fast time went by and thought it was fun. They actually asked to do it again.
Here is my balloon pop Powerpoint for solving systems of equations by substitution. I put the answers at the bottom of each slide and covered it with a white rectangle. Then I used the animations to make the box disappear and show the answer.