NeoVintageous Super keys
"Super" keys are disabled by default in NeoVintageous. You can enable them via the Command Palette NeoVintageous: Toggle SUPER keys. Super keys are more commonly labelled as a Windows key, or Command key (⌘) on Mac.
[!NOTE] Since v1.32 super-keys are enabled by default.
The key notation in Vim is <D-...>. For example, create a mapping:
noremap <D-i> :GotoSymbolInProject<CR>Case Sensitivity
In Vim, <D-A> and <D-a> are equal i.e. the case of {char} in <D-{char}> doesn't matter. But in Sublime Text all the keys are case-sensitive, using the shift key produces different key events. The advantage is that, unlike Vim, in Sublime Text you can create mappings for both <D-A> and <D-a>.
Key Handler
You can configure the key handler to ignore selected keys. Read the NeoVintageous Key Handler.
Troubleshooting
Operating systems make extensive use of super keys. When you find a super key is not working, the might be "shadowed" by a desktop key binding. In that case, Sublime Text won't be receiving the key event.
Debug the event by running sublime.log_input(True) in the console. Open the Sublime Text Console via Menu → View → Show Console. If Sublime Text is not receiving the key event, you will need to clear the desktop key binding. If you use Ubuntu reading Ubuntu Keymaps may help.