Mortal Kombat for the SNES wasn't really everybody's goto for home console versions.  Although it looked closer to its arcade counterpart, it ran very sluggish, blood turned to sweat, and some fatalities were changed altogether, even if Sub-Zero's did make more sense.  But it was either by nostalgia or feeling bad for the little guy that the modding community wanted to make it just a bit better to give it that edge.

Starting out as a Game Genie code the Blood Color Fix by DarkSamus993 was one of the earliest patches that turned the sweat to blood and although a small color change it does look better and does it's job.  About three years later Snark-4918 came out with Champion Edition which makes Reptile, Goro, and Shang Tsung playable characters.  Three more years later Snark-4918 came out with the second version which made it much better.  Click on the link and view the Readme to see how to use the extra characters and their moves.  Last but not least MSU-1.

NOTE: There is a revision of this game that fixes the sluggishness and plays much better but is incompatible with any hack except for an MSU-1 patch linked, not necessarily created, by Conn.  There is also a blood patch for it created by alex_tenjo but apparently he would need to be contacted for it but it has been about three and a half years since then.  There is also two uncensored versions of the Champion Edition, one for version 1 and the other for version 2, both incompatible with MSU-1 and the second version having some bugs and some fatalities not working.