Planting the bomb in Hardcore Search and Destroy on Call of Duty: Black Ops. Note limited HUD with exception of symbol showing possession of bomb as well as mini-map due to active Spy Plane.
It is considered one of the most difficult game modes to master due to the lack of respawning along with having no HUD. It is also made harder by the fact that the mode is often played by more experienced players, and that weapons are likely to kill players very quickly. Although it can be also deemed as quite easy as it only takes one (or occasionally two or three) shots to kill an enemy. Team Killing is seen more in this game mode as players do not respawn, and is more popular in Call of Duty 4: Modern Warfare as the player will not be removed from the game like Call of Duty: World at War. In Call of Duty: Modern Warfare 2 and Call of Duty: Modern Warfare 3, ricochet rules cancel Team Killing altogether. In Call of Duty: Black Ops, team killing in the first few minutes will automatically kill the player. This is to stop players killing a bunch of their teammates as soon as the game starts, to grief the other players, but maintains the "real" aspect of bullets in later game play.
As stated above, the game mode is somewhat modified in Call of Duty: Modern Warfare 2and Modern Warfare 3, labeled "Hardcore Ricochet S&D". It is still Hardcore Search & Destroy, except with ricochet rules. There is no team-killing, however, friendly fire results in slightly less damage the teammate received to be inflicted on the player instead, oftentimes killing them with the "Friendly Fire will not be Tolerated" notice. For example, if the player is using a suppressed weapon, 1 round won't kill, however, 2 rounds will. Hardcore Ricochet is also a variant in Headquarters.
In Call of Duty: World at War, it was possible to kill teammates and not get auto-killed or kicked (the player gets kicked from the game if they kill more than 3 teammates). The player had to have a Bouncing Betty out and knife teammates. This glitch has since been patched.
In Call of Duty: Modern Warfare 2, if a bomb is planted, and equipment such as a Claymore is used immediately afterwards, the bomb will be picked up again, not affecting the timer or bomb in any way, but will render the player unable to use his weapon, and can cost a life. Therefore, experienced players will place defensive explosives down before planting. However, this may expose the player to enemies using SitRep, who are then alerted to the chosen bomb-site.
In Call of Duty: Black Ops, if someone using Second Chance is killed at the end of round 3, 6, or 7, the game will drastically slow down during the transition when continuing to the next round or the pre-game lobby.
Many people think of this mode as the most realistic because of the lack of respawning and Hardcore rules.
As with all Hardcore gamemodes in Call of Duty: Modern Warfare 2, pausing the game and looking at the map when an enemy fires an un-silenced firearm will result in their red dot showing in the radar, exposing their position.
Grenade launchers are frowned upon in this game mode, because its an easy weapon to get spawn kills from shooting across the map.
In the Hardcore Mosh Pit playlist in Modern Warfare 2, Ricochet rules are NOT enabled, which has led to a large amount of team killing.
In Modern Warfare 2, the bomb planting/defusing animation is exactly the same as in Call of Duty 4 making the player look like he/she is punching 23, 23, 23, 23.
In Black Ops, the bomb planting/defusing animation is 115, 115, 115; 115. This is a reference to Zombies.