yep, it's been posted here on Introversion Lounge aswell, but i think he saw it in my signature. Check out my siggie, it's much more attracting, than his plain old link
Edit: I just scrolled down some more and found this topic : Click
I've always been amused by this one... Not so mucha hacking game so much as a set of static hacking challenges hosted on their server. Requires little to start, but some of the puzzles are ptretty tough...