Hacking is a very serious issue in the gaming world. If your hard work gets out there, in all it's binary glory, people will want to see it and take some stuff from it. Not only that, companies you've worked with to build the program, such as the Doll-rag feature a.k.a. The HAVOK engine, which is made by a development team in Germany, could of sued Valve for millions because parts of their code was in the leak. Most importantly, to these guys, their code was their life. If you knew 1/3 of your code was leaked, you'd delay the game until it's done. They said it them selves the game wasn't going to be finished by September 30th in an interview with Doug Lombardi at this year's E3, then the code heist happened...