Developers on sites like Itch.io have created independent versions, such as Minecraft 2 by strompy , which includes custom mini-games, weapons, and biomes.

This was a joke version released by Mojang years ago that included "blue chickens" and "super hostile" animals; it is not a real sequel. How to Download Official Minecraft for PC

Depending on what you are looking for, "Minecraft 2" usually refers to one of the following: