Disassembling Sublime Text
Ah Sublime2 was my first binary-cracking project. After countless hours of debugging with GDB and trying to understand assembly in Hopper I managed to disable the nag and patch the binary. (Purely for fun. I bought a license shortly after, of course I did not distribute this in any way). 
Will never forget how proud and satisfied I felt when it finally worked.<p>While mostly using Jetbrains or Atom with VIM plugin for development these days I still value Sublime for being able to handle really big files a million times better than Java&#x2F;Web based editors.