Hi, I have "hacked" many games and if by "hacked", you are meaning changing colours of walls, custom sounds, etc... Then I have. Take MC3 for instance. A good game, but I find that the songs are less than great. For that problem, I get my ISO on my PC (this only works with CSO if you change the file extension from .ISO to .CSO breifly) right click and select "open with" and select WinraR. I open it up, and locate the .at3 files. this is the games music. I then convert an mp3 file of my choice to at3 using one of many converters out there and rename it to the original at3 file you want to replace. I then drag the converted mp3 into the winrar window, and it will prompt you to replace it.
This is one of many ways you can customise or "hack" your games. I recommend a hex editor with a hex image viewer if you want to change the colour of walls etc... All you have to do is find the correct offset etc...
You can, if you want to, redesign the entire game this way and make a complete conversion. There are a few guides out there but they are hard to find. I will post a guide very soon.