$ sudo apt-get install mono

$ mono TwitterIrcGateway.exe
The assembly mscorlib.dll was not found or could not be loaded.
It should have been installed in the `/usr/lib/mono/2.0/mscorlib.dll' directory.

$ lm /usr/lib/mono/2.0
ls: /usr/lib/mono/2.0: No such file or directory

$ sudo apt-get install mono-classlib-2.0
$ mono TwitterIrcGateway.exe
** (TwitterIrcGateway.exe:4924): WARNING **: exception inside UnhandledException handler: An exception was thrown by the type initializer for System.Windows.Forms.Form

ねむい!