- Defeat all of the Hiddens to win.
This is a Team Deathmatch-based mode but with humans vs the Hidden, or Joker in some regions. In a round, a player will be randomly chosen as the Joker. The Joker is nearly-invisible on the start and loses his stealth after a few seconds. He is completely visible when attacking and will regain his invisibility when he successfully killes a human. He is only armed with a staff. In addition, he has high moving speed and jump, 300 health points and 100 armor points.
For humans, the humans must annihilate the Joker. The player that succeeded to kill the Joker will become the next Joker.
In this mode, money is not needed as weapons can be selected for free (similar to Deathmatch modes).
The match ends when the number of kills meets its target or the game reach its time limit, similar to Deathmatch.
As of 4 December 2014 update in South Korea, the Hidden is renewed with new items and rules.
- More than one Joker can appear in game: beside the main Joker, who is half-invisible, another player will be chosen randomly to be the extra Joker, or Betrayer.
- The Betrayer is disguised as a human. Furthermore, their movement speed, jump height and health points will be increased to match as the original Joker, but slightly inferior. This encourages players to keep moving and be aware of their surroundings more than before.
- Jokers have a Hidden Bar to show the time. When the bar runs out, another random player will be chosen.
- Humans can detect the main Joker when turning on the flashlight or by picking up the Hidden Detector.
- Supply Boxes were added.
- Mysterious Masks will turn one Human into a Hidden and give hiding skills and powerful strength for a certain time.
- The Hidden will respawn constantly even if he/she dies.
- After a certain period, the mask will move to another Human and an existing Hidden will turn back into a Human. Whenever a Hidden kills a Human, the duration will increase slightly.
- If the Hidden doesn't move for a certain time, their location will be shown on the radar.
- The Hidden looks transparent normally, but if a Human flashes a light at a Hidden, it becomes easier to see them.
- Some Humans can betray and attack other Humans due to threat of the Mysterious Mask and earn points.
- You are a Hidden now! The Hidden's power will disappear after a certain time. Your time will extend when you kill more people.
- A betrayer has appeared! The betrayer attacks Humans with a Hidden!
- You've betrayed Humans! Attack Humans with melee weapons.
- The Hidden have changed. You are a Human again.
- You can only damage with Melee weapons.
- The Hidden's power is running low!
- The Hidden's power has disappeared. Go back to being a Human.
- The Hidden's power has disappeared! The mask will go find a new Hidden.
- Someone has become a Hidden. Get ready to kill the Hidden!
- New Supply Box Items
- Sprint: Move faster than usual and replenishes players' ammo.
- Health Up: Doubles the default health points and will be restored continuously whenever their health is below 200.
- Critical Damage: Boosts player's attack power.
- Hidden Detector: Shows the Joker's location in the radar.
- Two primary attacks are needed to kill a human while only a single secondary attack is needed, but it's slower than the primary.
- Do not swing the staff too much as it will reveal yourself.
- Do not get close to smoke because your invisibility can be revealed easily.
- Strike from behind with secondary attack.
- Do not be greedy to kill humans. If the camping spots have 3 or more people, do not eliminate them if they already spotted you.
- Hit-and-run is the best tactic as a group of alert humans can easily spot and kill the Joker.
- AT4CS is the best weapon if player has been selected as Joker to make additional kills, this bug only works if he/she aims correctly to other players a second before he/she turns to Joker.
- Since Fun mode Re:boot, players can replenish the time of the Hidden Bar by killing humans with the secondary attack. Take into account that the attack is slower than the animation itself, so master its use before engaging humans.
- Original Jokers' secondary attack cannot take out multiple targets at once, any other nearby human will be sent flying away upon killing the targeted one.
- Disguised Jokers still possess their weapons, but the only way to annihilate the humans is with their melee weapon. Moreover, it does not matter what melee weapon they are wielding as one hit is enough to finish them off, so it is recommended to use melee weapons that can harm multiple targets at once.
- Disguised Jokers' name will be renamed so players can not easily spot them. However, as they remain using their human player model, it is more likely to be easy to spot as you can see them while respawning or they killed someone else.
- Humans are not recommended to stick together as Joker can camouflage into any human, take care of yourself and don't believe anyone. Notice the surrounding, report to your team if you spot the Joker.
- Original Jokers are nearly invisible, not fully. Use flashlight for easy detection, however, don't use it for too long as it will run out of energy.
- Snipers are recommended if all of the humans has hold each of their position. M82, M24 and XM2010 are recommended because they are accurate when move-while-firing. However, they are weak when the Joker is close enough.
- Shotguns are also threat to Joker if they can shoot while reloading, such as Benelli M4, SPAS-12 Superior and UTS-15. Moreover, they deal high damage too.
- Beware that the Joker's attack range is quite far so keep a distance.
- If you can't see the joker clearly, just spray the map with a high ammo capacity machine gun. Automatic sniper rifles are also recommended.
- AT4-CS is recommended because its rocket can chase the Joker. However, its damage will decrease over range and the rocket's homing ability is limited.
- BALROG Series are recommended: BALROG-VII and BALROG-III for their explosion damage, BALROG-III for its high rate of fire upon activating Balrog Charging System, and BALROG-V for its high damage.
- VULCANUS-5 is one of the useful weapons to kill and detect Joker.
- See the minimap on top of your screen to help you track the Joker.
- When a player becomes the Joker, listen carefully to his night vision goggle being turned on. This helps you to predict the location of the Joker.
- Both original Joker and Betrayer have high stun resistance to weak or normal weapons, look for higher stun weapons such as SKULL-5, SKULL-7, Volcano, etc.
- Predict the movement of joker as there will be more than 2 paths for a joker to run.
This mode was released on:
- South Korea: 8 December 2011.
- Taiwan/Hong Kong: 4 January 2012.
- China/Japan: 4 January 2012.
- Singapore/Malaysia: 19 December 2012.
- Indonesia: 16 January 2013.
- CSN:Z: 23 September 2014.
- Vietnam: 26 March 2015.
- This mode is based on a Half-Life 2 modification called The Hidden: Source.
- This mode resembles to a custom mod in Counter-Strike known as Ghost Mod. It is a bomb defuse mode where the Terrorists can only use knife but are invisible. This mode is officially released in Counter-Strike Online 2 as Stealth mode.
- After the Fun mode Re:boot, few features were already spotted in the promotional video for it such as the fact that the Joker can now disguise himself as a human.
- The Betrayer only appears when there are more than 4 players in a room.