Sharpness 25k Texture Pack (also known as the Sharpness 25k Milestone Pack

The rumors started on an obscure Minecraft forum thread that was deleted within minutes: a download link labeled simply SHARPNESS_25K.zip

A pack likely means:

Ensure you have Optifine or a similar performance mod installed for the best visual experience.

Due to the insane resolution, standard .png compression fails. The pack uses a custom .25k container format that splits each block into 256 tiles of 1,600x1,600px. Mipmaps are pre-generated down to 16x to prevent aliasing at a distance.