designed to look "broken" for entertainment (like creepypasta-style mods), or a technical error resulting from Understanding ROM Corruptions
Some "corrupted" downloads are actually carefully crafted ROM hacks like Reverse Curse Sonic 1 Corrupted Rom Download
Intentional corruptions are popular in the "glitch art" and retro gaming communities. Real-time Corruptors: Sonic 1 Corrupted Rom Download