Yes, I have heard the rumors of people hacking Hexic, and I have news from Major Nelson, of the launch team:
We’re seeing reports of people hacking Hexic HD using the European Kiosk disk hack. The truth of the matter is that we actually removed the code from the kiosk version of the game that awards achievements and Gamerscore and posts high scores so the reports are false. While Hackers can play the game and trigger the achievement awarded animation as if is still there but they don’t actually earn anything since they can’t connect to Xbox Live.
Source: Major Nelson