Even if the core engine is based on 1.8.8, the community surrounding Eaglercraft 1.20 content offers a surprisingly deep experience:
Because EaglerCraft emphasizes openness, modders can implement retro-inspired gameplay mechanics — from bespoke crafting systems to pure-redstone contraptions — without contending with heavy compatibility layers common in larger modding platforms. eaglercraft 120
Eaglercraft 1.2.5 is a port of Minecraft Beta 1.2.5 (specifically based on the "ReIndev" or "Classic" eras of the game) to WebGL/JavaScript. It runs entirely in your web browser. Even if the core engine is based on 1