Tom Clancy's The Division 2

After defeating Aaron Keener and completing the Warlords of New York story, you unlock directives, which are basically gameplay modifiers that, when activated, change the effects and dynamics of the game to further challenge the players. They also give you extra XP and slightly increases the chance for a targeted loot item to drop alongside a normal loot drop.
 
There are five directives available at any given time and you can activate up to five at once. Directives change over time. Past and present directives are:
 

• Ammo Hoarders: Reduced starting ammo and excess ammo is lost on reload. Enemies don’t drop ammo and ammo is not shown on the mini-map.
• Cool Skills: When one skill is activated the other is put on cool down.
• Fog of War Revisited: Mini-map and directional threat indicators are removed.
• Fragile Armor: Armor breaks apply a stack of “Broken” to the agent. Each stack of broken reduces an agent’s max armor. Using an armor kit removes one stack of Broken.
• Hard to Earn: Start with no Armor Kits. Only acquire Armor Kits by filling the Signature Weapon ammo bar.
• No Regen: Armor never regenerates after an encounter. It can be manually healed.
• Pistolero: Start with no ammo. Hostiles killed with a sidearm are the only ammo source.
• Ragers: Killing an enemy fills the Rage Meter of nearby hostiles. Rage depletes over time. A full Rage Meter makes an enemy “Enraged” (which grants overheal). Killing an Enraged enemy removes all the rage from nearby hostiles. An empty Rage Meter makes an Enraged enemy return to normal.
• Scavenged Skills: Skill cool downs are only reduced by collecting Skill Parts from killed enemies and destroyed weak points.
• Special Ammo: Enemy bullets may be of special types. What type depends on the enemy faction.

For this achievement, you only need to activate one directive then complete one of the five main missions in the expansion. You can replay the mission on any difficulty.
 

• The Tombs (Civic Center) - Theo Parnell
• Pathway Park (Battery Park) - Javier Kajika
• Wall Street (Financial District) - James Dragov
• Stranded Tanker (Two Bridges) - Vivian Conley
• Liberty Island (Financial District) - Aaron Keener

 To select a directive, press  to open the map and press  to open the ‘Global Settings’. From here, you can change the difficulty, activate directives and reset Control Points. Note that only the host can activate a directive; it will be applied for everyone else in the group.
 
It is recommended that you either host or be in an established group before attempting this achievement. If you use matchmaking to find people playing a mission, it is very possible that they might not have a directive active.