Et avec cet article j'ai pu également télécharger les apps necessitant la camera frontale sur mon iPhone 3gs;
Comme angry bird go, retrica, plant vs zombi 2, ninjajumps rooftops...
Voila l'article en anglais 
Install iFile via cydia. Open iFile. Go to System/Library/CoreServices/SpringBoard.app. Tap K48AP.plist (for original iPad) or N88AP.plist (for iPhone 3GS) and choose Property List Viewer. Tap "capabilities." Tap + in the lower-right corner. Name it "front-facing-camera" (all lowercase, without the quotes). "Type" is "Boolean." Tap the "Create" button in the upper right. Change the value from off to on in the list, tap done. Reboot (not respring). You should now be able to install the game.