From Monkey Island wiki
LUA is the programming language used for Grim Fandango, Escape from Monkey Island, and Tales of Monkey Island. It is the scripting language used for the GrimE graphic-engine which replaced the SCUMM engine used for most if not all of LucasArts's adventure games up till that point. It is also the scripting language used in the Telltale Tool by Telltale Games. It is referenced in Escape from Monkey Island when the SCUMM Bar is replaced with the Lua Bar.