Many successful projects that we see online are not brand new. Instead, they have just improved upon existing ones. Take the case of these excellent custom ROMs for Android. They are based on the stock ROM that ships with tablets and smartphones with the Android OS. But by eliminating unnecessary features from the original, providing more control over the existing ones, and adding other useful tweaks, the custom ROMs have gone on to become quite popular.
A word of caution is required here. If you decide to adopt this method, do ensure that you’re not infringing on anyone’s copyright.