For the perk in Call of Duty: Black Ops, see Hardened (perk).

"Your skills will be strained."

— In-game Description

Hardened is one of the four difficulty settings in the Call of Duty series. It is harder than Recruit and Regular but easier than Veteran. It is recommended to play on Veteran, seeing that health is already low, and player can earn more trophies or achievements, typically those requiring the completion of a series of missions on Veteran. In all of the Call of Duty games to have achievements, the one achievement that can be unlocked only by playing on Hardened but not requiring Veteran is the large achievement for finishing the campaign on either of those difficulties.

On Hardened, players have less health than earlier difficulties, and the AI is slightly more accurate and effective. The enemies won't assault the player with as many grenades as on Veteran. In Call of Duty: Modern Warfare 2, the player's aim will kick up when shot on Hardened, albeit not as much as if the player was on Veteran. When killed by a grenade, the player will usually not be told what killed him. When the player has little ammunition in his/her clip, the player will not get a warning that says to reload.

In Call of Duty: Black Ops, the image applied to Hardened features a soldier bearing his teeth in front of what appears to be six missiles.

Difficulty Levels in the Call of Duty Series
Recruit - Regular - Hardened - Veteran