Did you know that every time you beat Contra, the game gets gradually more difficult on each subsequent loop? This patch maxes it out to 255 and makes for an interesting playthrough.
That sounds pretty basic, so why is this a patch? Well, it would've been great to fit this into simple Game Genie code, but unfortunately it's not that easy. The game completion counter gets initialized with a whole range of values whenever starting a new game, and there's a very small window where changing it will actually take effect. Normally it only increases after beating the game, then warps straight to level 1, thus bypassing initialization.
I hope you enjoy the added challenge! If you like this patch, I am working on another that also leverages this functionality. You're welcome to use it for your own purposes, too!