I want vim to open up the :Explorer when no file is opened or created. Eg. when I call vim without any options.
calling vim newfile.txt should still behave the normal way though.
How would I go about doing this? I can't seem to find the correct autocmd for it.
If you want to do this for vim invocation only, the best way is to use argc():
autocmd VimEnter * :if argc() is 0 | Explore | endif
argc() function returns a number of filenames specified on command-line when vim was invoked unless something modified arguments list, more information at :h argc().