Metal Gear Solid 2: Sons of Liberty (Demo Disc)

Even the stealthy sometimes get caught. When this happens, a blue exclamation point will appear above the guard's head. If you shoot the blue punctuation mark, you'll knock the guard out temporarily.

Anytime you find yourself hanging from a bar or edge, go into first person mode. By pressing R2 and L2 at the same time, Snake will do a pull-up. Do 100 of them and Octacon will tell you that your Grip Strength has been improved.