When I play games on my iPhone 4 will it use my data?

When I play games on my iPhone 4 will it use my data?

Only while downloading the game or playing multiplayer should a game use any data(or submitting a score, I suppose).So games like words with friends would use some data. Single player games like fruit ninja would not.

IF it is an ON LINE game, YES.

The use of data depends if the app wants to connect to the Internet or not. Social games such as Ruzzle always connect to the Internet, while other games like Angry Birds do not require Internet connection at all. You can check to see if the app needs Internet connection by switching your phone into airplane mode and opening the app to see if it works.