Hardcore

Hardcore mode is an alternative to the normal playlists in Call of Duty 4: Modern Warfare, Call of Duty: World at War, Call of Duty: Modern Warfare 2, and Call of Duty: Black Ops. As the name suggests, the gameplay is much more testing and realistic, with the following implications:
 * Significantly less health - Players can only withstand 30% of the damage they could in normal modes before dying or going into Last Stand/Final Stand/Second Chance.
 * Limited HUD - Nothing in the way of displays shows unless a UAV/Recon Plane/Spy Plane/SR-71 is called, in which the map in the upper left appears. It promptly disappears when it expires. However, in Modern Warfare 2, the map is available if The player brings the menu up. Since players are not notified when they are over a dropped weapon they could pick up, weapon stealing seldom occurs. Exceptions to this include green text identifying teammates, a symbol that the player is carrying the bomb in Hardcore Search and Destroy, or the display of flags in Hardcore War and of the HQ location in Hardcore Headquarters. In the hardcore Wii version of Call of Duty: World at War, there is a white dot used as a reticule in the game. In Modern Warfare 2, all notifications (upper right corner of the screen) of players calling in or destroying killstreaks, achieving match targets or other notifications such as triple kills are disabled. There are two exceptions to this: players will be notified if someone copies their class or if someone destroys their tactical insertion.
 * Friendly Fire on - Teammates can be killed just as easily as enemy players. If this happens, the same point total earned for a kill is deducted from the team-killer's score, although at the end of the game such penalties are not included. Deliberate team-killers are punished; in Call of Duty 4, a player is automatically killed and sat out for a period of time after 3 or more team-kills. In Call of Duty: World at War, a player is removed from the game entirely after three team-kills, excluding those from artillery or bouncing betties. Modern Warfare 2 returns to the same rules as Call of Duty 4, but friendly fire penalties are sometimes harsher (as much as 3 minutes for a RPG team-killer at the beginning of the round). Also, if a friendly fire penalty is triggered while using an AC-130 or Chopper Gunner, the killstreak will end. In Black Ops, the rules return to that of World at War, and players who score three teamkills in one match are removed.
 * Hardcore Ricochet - In Call of Duty: Modern Warfare 2, Hardcore Ricochet game modes replace Hardcore versions of Search and Destroy and Headquarters, where instead of team-kills occurring with friendly fire, the player committing the friendly fire takes the same damage he inflicted on the teammate, which could mean getting killed. Team Deathmatch and Mosh Pit are the only game modes in Modern Warfare 2 with normal Hardcore rules however the Hardcore variants of Search and Destroy and Headquarters found within Hardcore Mosh Pit still use Ricochet friendly fire.
 * KillCam - A killcam is not shown to the player after death. This benefits players who like to be stealthy and hide in concealed locations, since it will not be made immediately obvious to the victim where his enemy was. Theoretically, a well concealed marksman could stay hidden for an entire game, although the view will still zoom in on the killer afterwards.
 * Respawn Delay - There is a respawn delay while playing Hardcore Team Deathmatch; this delay is not present in regular Team Deathmatch game types.
 * Motion Sensors - Motion Sensors and Jammers are almost completely useless due to the fact there is no permanent mini-map.

Game modes available
In Call of Duty 4: Modern Warfare In Call of Duty: World at War In Call of Duty: Modern Warfare 2 In Call of Duty: Black Ops
 * Hardcore Team Deathmatch
 * Hardcore Search and Destroy
 * Hardcore Headquarters
 * Hardcore Team Deathmatch
 * Hardcore Search and Destroy
 * Hardcore War
 * Hardcore Headquarters
 * Hardcore Free-for-All
 * Hardcore Ricochet Team Deathmatch
 * Hardcore Team Deathmatch
 * Hardcore Ricochet: S&D
 * Hardcore Ricochet:HQ Pro
 * Hardcore Mosh Pit
 * Hardcore Team Deathmatch
 * Hardcore Search and Destroy
 * Hardcore Free-for-All
 * Hardcore Headquarters
 * Hardcore Capture the Flag

Exclusion in World at War
As mentioned above, a player is removed from the game after three team-kills, with the exception of artillery, bouncing betties, or if a bomb they planted in Search and Destroy kills a teammate. If this happens the player will also not be able to re-join the game session by joining the players in progress. However, the host player cannot be kicked, due to the game's inability to host migration during game. But, much like Call of Duty 4, the host player will be killed off and sat out of the game for a period of time.

Announcement
When a player gets booted from the game, regardless of whether or not it was a teammate or enemy player, the game's announcer will make a statement, even if it is the host player who doesn't actually get kicked. There are two such statements for each of the four factions players can play as:

Red Army: Wehrmacht: Marine Raiders: Imperial Army:
 * Cowards and traitors will be dealt with severely!
 * Such a man has no place in this army!
 * A teammate has disappointed the Führer! You will not see him again!
 * Your teammate has disgraced us all. He will be dealt with, harshly!
 * He ain't fit to wear the uniform!
 * Get that son of a bitch out of here!
 * A teammate has abandoned the path of the warrior!
 * He brings only shame to his family!

Exclusion in Black Ops
Similar statements upon a player getting kicked are made. Examples include:

Black Ops
 * That son of a bitch isn't fit for the mission! Get him out of here!

Op 40:
 * Get that son of a bitch out of my sight!

Tropas SOG: NVA: Spetznaz:
 * Such insolence will not be tolerated! Execute that man!
 * Get that son of a bitch out of here before I kill him myself!
 * Cowards will be punished!
 * Traitors like that sabaka ("dog" in Russian) will be dealt with!

Tips

 * A stealth class is excellent in a Hardcore mode, especially on HC Free-For-All. A good stealth class in MW2 would be an ACR/FAL w/ Red Dot/Holographic Sight and/or Silencer, or a sniper rifle w/ silencer, any secondary weapon except a launcher, with perks Marathon/Bling, Cold Blooded Pro, and Ninja. This makes the player mobile (with Marathon) or versatile (with Bling and the correct secondary weapon choice), undetectable (Cold Blooded covers thermal sights/killstreak attacks, and the Pro version makes it easier to hide undetected, and even easier with a ghille suit), and resistance to the Heartbeat Sensor with Ninja, while the Pro makes the player's footsteps inaudible. In COD4 would be a G3 or M14 with silencer, USP .45 with silencer, with perks Claymore x2, UAV Jammer, and Dead Silence. It will make player undetectable, silent, and give him protection.Also G3 or M14 are very useful because they can kill an enemy in 1 shot.In WAW it would be Bouncing Betty x2,Camouflage and Dead Silence,a semi-auto rifle like the SVT-40 or Gewehr 43 with flash hider/silencer and a Tokarev, similar to class in MW1.In BO it would be Ghost,Warlord and Ninja perks with WA2000 with ACOG and Silencer and a Makarov or CZ-75.
 * Another class, which is similar to a rusher class, would be a weapon that can easily do damage equivalent to amount of HP of the enemy in Hardcore (like the UMP/AK-47). Perks is recommended to be Marathon, Lightweight, and Commando/SitRep/Ninja (Pro versions of these perks are highly recommended due to their additional effects). This class gives the player extremely high mobility, defense against Claymores/C4 and (if Pro versions are unlocked), fast killing rate after sprinting, better mobility (no falling damage means easier moving about), and Claymore explosion delay.
 * In terms of Killstreaks, UAVs/Recon Planes/Spy Planes are a must. They provide radar and give away locations of any un-stealthed enemies and aircraft, if any, in the air that an anti-air teammate can locate and shoot down. Use Hardline to get them up faster and more frequently, though the player will have to sacrifice their stealth perk as a cost. Preferrably, Care Packages can often give the player another UAV, or ammo if they are not using Scavenger. Sentry Guns will kill unstealthed enemies, but can also be used to lure stealthed enemies that will destroy it. Try to keep away from Predator Missiles, Airstrikes, Chopper Gunners, and AC-130s as the player may accidentally kill their teammates, or even themself, in the process, but it comes down to preference on how to provide support. Attack Helicopters and Pavelows with their gun turrets are more accurate against unstealthed enemies. A Tactical Nuke is nearly impossible to obtain as the player will die more easily in Hardcore mode, so it is mostly avoided as it would only waste a Killstreak slot for something more useful.
 * The Perk Scrambler or the killstreak Counter-UAV is nearly useless in Hardcore due to the radar only showing up during a UAV, which is not common at levels 10+ onwards.
 * Guns with low damage per bullet is ill-advised, unless they don't have any other drawbacks. Guns with a higher damage rate will easily kill enemies in one or two shots, while guns with low damage needs more shots.
 * Claymore is good during Hardcore matches since the explosion from any proximity will kill the victim, though SitRep/Hacker can be used to counter this.
 * Danger Close is not recommended unless dealing with killstreaks as the normal explosive damages will kill players easily.
 * Hardcore can be used as a resource to get weapon attachments that otherwise would be difficult to achieve. For example, the sniper rifles with silencers would (in core) be quite difficult to get a one shot kill with; in Hardcore, it becomes easy. It is also easy to receive XP from perk challenges, as Stopping Power is not needed.
 * Heartbeat Sensors are very good alternative for the missing radar, though not as effective.
 * Watch for teammates before using any weapons with splash damage, as the splash damage may kill the player's teammate.
 * Last Stand/Second Chance or Final Stand can be a difference between a kill or a death, as the pistol damage can easily kill an enemy.
 * Only use an EMP when there is an enemy killstreak in the air, as the HUD is already disabled in Hardcore modes, meaning the only thing the EMP can do is to destroy killstreaks and reducing some of the effects of attachments (though mostly negliable).
 * Reconissance perk is nearly useless since minimap is already disabled, and a Recon Plane will be called approximatelly only 2 or even 1 time in 3 minutes.

Trivia

 * In Call of Duty: Modern Warfare 2, many people use Hardcore as an easy way to unlock Extended Mags since only 2+ shots through cover is needed to take down a target, compared to 3-4+ in regular game modes.
 * Camping is usually utilized in Hardcore modes because of the missing minimap and killcam.
 * Call of Duty: Modern Warfare 2 originally featured Hardcore mode for all playlists, but it was cut because of dedicated servers removal.
 * In Call of Duty: Modern Warfare 2, players often use the Heartbeat Sensor attachment as an alternative to the mini-map.
 * New players may think that Hardcore does not give any EXP points due to the missing EXP counter when a kill is scored.


 * In Call of Duty: Modern Warfare 2, killstreaks can become less effective as the damage multiplier means Stopping Power isn't as vital to get kills and Cold Blooded is used more frequently. This can also lead to team killing and an end to the player's killstreaks when using Predators, AC-130s and Chopper Gunners by mistaking team mates for enemies using Cold Blooded.
 * In Call of Duty: Black Ops, the player can kill friendly players indefinitely as long as they are the host. This is a popular pastime for griefers.