Survival horror is a subgenre of action-adventure games. Although combat can be part of the gameplay, the player is made to feel less in control than in typical action games through limited ammunition or weapons, health, speed, and vision, or through various obstructions of the player's interaction with the game mechanics. The player is also challenged to find items that unlock the path to new areas and solve puzzles to proceed in the game. Games make use of strong horror themes, such as dark mazelike environments and unexpected attacks from enemies.