Startup Idea : Universal OS Program installer.

The problem is that with the hundreds of operating systems that exist out there, nobody wants to develop software for more than one or two of them. The solution I think, is to develop a universal API, that is not directly developed for any specific OS, but with it, the producers of any said OS can take the API and easily implement (Finish) the API by completing the incomplete methods in the API for their OS and either have the API pre-installed on the OS, or have an option to install it easily. Then, developers around the world can develop their programs with the Universal API and then it can be installed onto any OS that supports the Universal Installer.