Game is not running on lower android devices

We have created a 2d game. After completing the game we tested it on Samsung Galaxy S3.The game worked flawless but it is not working on lower android devices like Samsung Galaxy Y. Can anyone help me to solve my problem, what should I do now I want my game to work on as many devices as I can

Regarding compatibility please keep in mind that Intel Atom processor is not supported, only ARMv6 in Unity 3.5, and ARMv7 in Unity 4. Samsung Galaxy Y has a 830 MHz ARMv6 CPU, so you might need to convert your project to Unity 3.5.x. You can find this version here:

Try a simple test first to make sure it works.