I installed Admin Block Country on two of my sites. It's working but one feature is not.
It says it won't include my own country but United States is included in the list. I almost "selected all" because I only want to allow US computers on my site. That's when I noticed United States was included in the list. Luckily, I deselected it.
I'm sure it's an easy fix for you to include in an update. It's a great, easy to use plugin, by the way. Perfect for my company.