Just released a very small hack. Creating this thread for it.
This is the official hardest mode by Konami.
If you're tired of beating Contra with your eyes closed, or tired of beating the game 6 times in a row just to get to the harder levels, I've made this hack for you. Every loop is the hardest possible version of the game. The final level is especially difficult. I won't get into details, but I get the feeling that it's the way the last level was originally intended to be played, then it was toned down by the devs during testing.
It's for the japanese version only, compatible with the translation. It also features the camera fix for 2 players mode discovered by dougeff.http://www.romhacking.net/hacks/4884/
RAM location $31 counts the loops. At first I just set this to a high value on each loop, but this breaks the flag counting on the helicopter at the end. Then I reverted that and went through the game's code to replace the reads from $31 with hard set values on a case by case basis. There were only about 7 or 8 occurrences. Usually they were only comparing $31 to 0, 4, or 6. There was one case where it added to another value, I'm not sure what for. I made it so it added to a high value instead of overflowing to a low value.