Allow User to Change the Exe
Create an iron python script for the game's Custom Icon event with these lines. Check "Prompt for variable values" and allow user access.
ThisService.Executable = ThisService.RootDirectory + ThisService.Variables["CustomExe"]; ThisService.Save(); ThisService.Configure();
Create a new variable named "CustomExe". In the variable settings tab check "Script parameter" and "Save script parameter value". Allow user access. Set the type to Combobox. Add an item for each exe that you want to allow.
With that your user should be able to see the icon in the service home page to change the exe.