Tactics
From DoomRL Wiki
The tactics system allows the player to switch between three states: cautious, running, and tired.
Cautious is the default tactic, and applies neither penalties nor bonuses. The player can switch from cautious to running, an action that takes 0.1s.
The running tactic offers some benefits and some penalties. The player gets a +30% movement speed bonus, a +20% dodge bonus, and enemies receive a -4 attack penalty to all attacks against the player. Additionally, damage from terrain (e.g. lava) is halved when running. To offset these advantages, the player receives a -2 accuracy penalty to ranged attacks, and his melee damage is halved. Running lasts for 30 actions (including the switching tactics action) after which tactics change automatically to tired. The player can instantly switch from running to tired at any time before this.
The tired tactic doesn't have any penalties or bonuses except that tactics can not be changed when the player is tired. In order to change his tactics back to cautious, the player must either go down the stairs to the next level, or use a health recovering item.
In addition, relics can only be used if the player is cautious or running. Some alternate fire modes also can only be used if the player is cautious. Using such an effect changes the player's tactic to tired, so the effect can not be used again until the cautious tactic is restored.