Creating an Aimbot

Very clear and to the point. One thing that I feel might be overlooked (I might have skimmed too lightly) is how this code will actually be executed. Is the binary being executed being modified?

The post specifies attaching to the process using a debugger and "we can call whatever functions we want in the interface and the game will act accordingly." Is arbitrary extra code simply a feature of some debuggers that I am unaware of?