This is a Sublime Text package which includes a bunch of handy snippets for doing Mootools development.
With Package Control
If you have the Package Control package installed, you can install Mootools Snippets from inside Sublime Text itself. Open the Command Palette and select "Package Control: Add Repository", then input this repository url. Reopen the Command Palette and select "Package Control: Install Package", then search for Mootools Snippets.
Without Package Control
If you haven't got Package Control installed (seriously, go install it!) you will need to make a clone of this repository into your packages folder, like so:
git clone https://github.com/chriswong/sublime-mootools-snippets.git Mootools-Snippets