Why is the 'Run' button in Monodevelop is grayed out?

I am following this c# tutorial http://www.unifycommunity.com/wiki/index.php?title=Programming_Chapter_1 and I’m just about the finish the Monodevelop section. Building my project was successful. I linked thescript1.cs file, added the reference to the unityengine.dll fine and built the project fine. The problem is that the Run icon is grayed out so I can’t run it.

Any ideas why this is happening?

I don’t use MonoDevelop (I use Visual Studio), so this is a shot in the dark. If it’s wrong, bear with me. :slight_smile:

I think your run button is grayed out in MonoDevelop because in programming environments outside of the Unity Editor, the code you build compiles into a class library, not a stand-alone executable. That is, the project builds into a DLL-file when you build it in MonoDevelop. You can’t run a DLL file directly because it doesn’t have a main-method. Instead, the purpose of such a file is to provide classes and methods to another program, namely the one built and run by the Unity Editor.

To run your program like the tutorial instructs, use the play button in the Unity Editor, not in MonoDevelop.