 Certain skills can be upgraded twice, enhancing the protagonist's abilities beyond those of the characters from previous games.Enemies can now hear the protagonist's footsteps if he or she runs too close to them, and they may hear the footsteps from a greater distance if the protagonist runs on noisy surfaces such as a puddle of water.They can also smell the protagonist if he or she falls into a cesspool (only found during some missions; after the protagonist emerges from the cesspool, a brown haze surrounds him or her, indicating that he or she can be detected by smell at a certain distance) or is covered with blood from an earlier fight.