By Al Giovetti
Ripper The Official Strategy Guide, Prima Secrets of the Game
If you have trouble getting by the ice in Catherine' Brain, go to the options panel and select the easy level, where you need hit only four of the 20 targets to succeed. You can also get past the ice by engaging the milestone chart. From the options menu, put your mouse cursor over the power button located in the lower right hand corner of your screen, then hold down BOTH shift keys on your keyboard and left click at the same time. From this chart you can tell the game you have finished any milestone and proceed to the next part of the game.
ReferencesPrima's Ripper: The Official Strategy Guide Web Site