This document describes techniques for allowing a computing device that provides a minimal execution environment to execute legacy applications that rely on rich functionality that the computing device does not natively provide. For instance, a device may initially receive a request to execute an application and may determine whether the application is directly executable. In response to determining that the application is not directly executable, the computing device may determine whether the application specifies another application to provide the functionality. If the application specifies another application to provide this functionality, then the computing device retrieves the specified application and executes the specified application on the client computing device. If the application does not specify such an application, then the computing device may execute a default application for providing the functionality. The specified or default application then executes the application that is not directly executable on the minimal-execution-environment computing device.