The game is simple. I keep my counting cubes separated into different colours, and I have several of these little blue jelly moulds (from Home Bargains) that I keep different colour cubes in. This game comes in a 2 dice version and a 3 dice version (a bit more challenging). The picture is of the 3 dice version.
Kids play in pairs (or in trios, if you have an extra kid). The first one rolls 3 dice and adds them up. They then cover the total number with a cube (so 6 + 4 + 2 would cover '12'). The next player then plays. If they roll a 12, they 'Bump' the other player off (remove their cube and replace it with one of their own). If they roll a different number, they can cover it with a cube.
As you can see in the picture, one number is covered with 2 cubes. If you roll the same total twice (or more times!) you can add an extra cube. Once that happens, that number is 'safe', and you can't be bumped off. At the end of the game, the player with the most numbers covered wins.
Kids really enjoy this little game, and so many kids need engaging ways to practice their number facts. The pictures below are clickable (you only need to click one picture - both pictures will take you to the same file, which contains both versions of the game), or you can get your copy of the game here.
One caveat - this really works best if you are combining this game with number talks that teach kids different strategies for adding. If they are just counting the number of dots on the dice each time, it isn't going to be as effective at improving number fact fluency. I usually teach this game initially in small groups where I can observe and encourage them to use addition strategies. We play it (with me observing) several times before I move it out to be an independent station.
Any questions, please ask! And if you use this, I'd love to hear how it works in your own class.