Minecraft is not an official release from Mojang but a popular fan-made "creepypasta" version of the game. It is widely reviewed by the community as a "cursed" or "horror" experience designed to unsettle players. Key Features and Experience
Alpha 1.2.6 had introduced the Nether one month prior, so in 1.2.7 it was still a terrifying, unfinished place.
The reason "1.2.7" often appears in searches or file names is due to or old mapping tools.
To understand why people were fascinated by this version, you have to look at the official Alpha 1.2 update (The Halloween Update)
: Animals supposedly appear with missing limbs or multiple faces, such as three-faced pigs or cows without heads.
: Players report trees without leaves, the sun and moon switching places, and the Minecraft logo appearing as wooden planks instead of stone.