Now, let's connect that to your goal. An "unblocked" game isn't a special, different version. It simply refers to any method that allows you to play the game on a network where it's officially restricted.
Download a "portable" version of Java 8 (the required version for Minecraft 1.12.2). Move both folders to a USB drive or your cloud storage. minecraft 112 2 unblocked new
If you have a USB flash drive and access to a personal home computer, you can create a "portable" Minecraft ecosystem. Now, let's connect that to your goal