Walls commonly feature in all mission locations. Besides the expected obstacle to one's movement and sight, clumsy players can slam against walls while sprinting (pressing "O"), this will make noise that, if heard by enemies, will make them check the source of the noise (more than one attempt may be needed); if the player slams agains walls too often or with enough force, they will be knocked unconscious for a few seconds.
Players can silently slide along walls if by pressing L1 (crouch) near one. A special stealth kill animation will play if the player catches an unaware enemy while hiding behind a wall.
A common bug in the game is for enemies to become stuck in walls while trying to return to their patrol posts.