The "upd" means you are looking for the latest stable version of the 1.8.8 branch.
One of the biggest limitations of older Eaglercraft builds was the render distance. Due to browser memory constraints, players were capped at 8 or 12 chunks. The 18 8 upd leverages modern WebGL optimizations to push render distances to 24 chunks. You can now see mountains and oceans in the distance without stuttering. eaglercraft 18 8 upd
Since the update is community-driven, bugs exist. Here are the top three issues and fixes: The "upd" means you are looking for the
Error 1: "WebGL not supported"
Error 2: "World failed to save"
Error 3: "Server timed out"