Sonic the Hedgehog 4 can refer to...

  • Sonic Crackers (this game was rumored to have been the Sonic the Hedgehog 4, which many believe is false as the Sonic the Hedgehog 3 sprite isn't used in this game)

  • A pirated Speedy Gonzalez game for the Super Nintendo that was modified to include Sonic in place of speedy and Marios in place of the captives. The game freezes in one of the levels due to a bug. Other levels can be accessed by hacking a savestate.

The ROM was dumped by TSD, a person whose name is an anagram of STD.