My iphone won't output sound threw speakers?

Hi, my iphone won't output sound threw the speakers when playing video games… But will output ipod audio, and ringtones, and some voiced apps.
I have seen it play the game music before threw the speaker… I don't know why it has stopped…

first generation ipod… Ios6

I had this problem back when i was an iphone noob. If you have an iphone, you may have turned the ringer/silent switch off(left side of iphone next to volume buttons). Or go into settings>sounds and something there may be off.