The creator, lax1dude , hosts the original source on GitHub. While GitHub is sometimes blocked, it often isn't. Look for lax1dude/eaglercraft and download the stable-download/ HTML file. You can save this file to a USB drive and open it locally.
Before you dive in, you need to understand the risks. unblocked eaglercraft
There are two primary methods to play Eaglercraft: playing directly on a hosted website or downloading an offline version. The creator, lax1dude , hosts the original source on GitHub