CSO

NOTICE Any updates placed here in advance are speculative and subject to change.
Do not take them as absolute truth until the update in question comes out.

See updates from 2016-2019: Events (South Korea)/2016-2019

Season

New Weapon Enhancement

New maps

Ruin (de_ruin)

Reworked maps

20 January 2022

Updated Competitive Zombie modes
Released Cargo Ship
Updated Zombie Z with new unlock level and some mutation adjustments
Renewed Continuous Mission System
Held Stingray Kite, Bonus Disassembly and Mileage Auction events
Updated Battlefield Supply
Fixed various bugs, noticeably Abyss2 and Episode Victor spawn bugs
Released Zombie Damage Meter
Adopted Quantum Horizon and Psychic Sizer
Held Power Energy event

6 January 2022

Improved SKULL-T9 performance
- Increased Range, B mode damage, Rate of Fire and portability
- Readjusted its Zombie Z level
Fixed some bugs

2022

30 December 2021

Held Mileage Auction
- Added Infinity Laser Fist
Adopted SKULL-T9
Added Private Erica, Drill Instructor Gerard, Boss David Black and Special Agent Criss to Rotation group in Class Decoder

16 December 2021

Released Skyscraper (Xmas)
Rereleased Italy (Xmas)
Added [Competitive] rules for Zombie Hero and Zombie Z modes
Added Harbor
Held 2021 Season 11
Held League Season 7
Updated Zombie content
Improved Family system
Held Christmas event
Held New/Returning plaers welcome attendance and Adieu 2021 ! Snowflake Collection events
Resold Magnum Launcher, Trinity Grenade, X-TRACKER and Lightning Fury to Rotation group in Transcendence Decoder
Resold Leader Soi and Super Soldier Jennifer
Added Aetheris, Axion, Medea and Kal-el permanently into Class Decoder
Added Point Transcendence Decoder and Point Class Decoder
Removed Rare grade weapons from Transcendence Decoder and Event Decoder

2 December 2021

Added Part System to Green Dragon Blade and SKULL-11
Unlocked Blade Frostbreaker for +5 Weapon Enhancement
Held Find the Zombies event
Resold Demonic Scarlet Rose
Held Let's spend the year-end together! and Let's run together! events
Replaced Magnum Drill with Infinity Laser Fist in Transcendence Decoder

18 November 2021

Added [Random Transformation] Zombie Scenario event for Paranoia and Lowdown
Released Void Zone
Improved Expedition and Family systems
Held Mission Clear and Playtime Pileup events
Recruited Roy and Romi
Fixed various bugs

11 November 2021

Extended Mileage Auction period by one more week
Fixed various bugs

4 November 2021

Improved Plasma Gun and SKULL-1 performance
- Added Part System to both weapons
- Increased damage in Zombie (Plasma Gun only) and Scenario (Plasma Gun and SKULL-1) modes
- Updated their Zombie Z levels
Held Mileage Auction
- Added Dual Beretta Gunslinger
- Held 1111 Mileage Special Auction Event
Resold Negev NG-7 Ajax
Added Dual Beretta Gunslinger permanently to Transcendence Decoder
Removed Desert Eagle Crimson Hunter from Transcendence Decoder
Held 1+1=11 Let's Get Together and Special Mission Completion events
Re-added and updated Experience Up
Updated and resold Zombie Z Starter Package

21 October 2021

Improved Zombie Escape
Released [Remains] Studio Zombie Escape map
Added Jungle theme blocks
Held Studio Jungle Theme Contest
Released Vertigo Halloween
Rereleased Assault Halloween
Adopted Laevatein
Held Bonus Disassembly
Held Halloween event
- Added Halloween Nameplate
- Held Pumpkin grenade and pumpkin head consume events
- Held Halloween Basket Collection event
Updated Battlefield Supply
Fixed various bugs

7 October 2021

Held Random Rule Zombie Hero
Held Autumn Leaves Box Collection event
- Added Autumn Leaves Nameplate
Added Transcendence Enhanced Weapon Selection Box
Added 50 EXP Weapon Enhancement EXP Coupon

30 September 2021

Improved Failnaught perfomance
Added Class Voice Emphasis to Audio Options
Fixed various bugs

16 September 2021

Released Electron
Added Class Change feature: Press [H] to change your class next round
Held Fireworks Crafting Festival! and Gather Sky Lanterns and Get Rewards! events
- Added Night Sea Nameplate
Held Mileage Auction
Adopted Failnaught
Recruited Ishmael and Ethan
Fixed various bugs

9 September 2021

Held Full Moon event
- Hunter Killer X-7 (Gun Boost 6, Rage Down 6) as the top prize

26 August 2021

Held 2021 Season 10 event
Added [CSO Brand Hip Color] costume to Black Market
Adopted Gear Bird Cannon MK-1, Gear Bird Cannon MK-2, Gear Bird Cannon MK-3, and Grand Bird Cannon
Held League Season 6
Adopted SG552 Cerberus
- Held SG552 Cerberus Collection Event

12 August 2021

Held Random Zombie Hero event
- New weapons: Blaze Nova, Twin Shadow Axes, Astra, Satellite Mine, Blue Storm, M2 Devastator, Elemental Tracker, ~~MG4~~
- Event destination maps: Assault, Italy, Dust
Held JANUS Is Back event
- JANUS-3 has increased damage
- JANUS-9 has increased damage and range
- Other JANUS weapons have increased damage and shorter activation count

29 July 2021

Released Lowdown
Updated Studio Play:
- Added Level and Difficulty rules
- Added Cutscene Camera device
- Expanded Ranking Board function
Released Researcher Journal #7: Tracking
Held Studio Zombie Scenario Contest
Improved info accessibility and user convenience
- Changed Playroom to Zombie Z Base
- Updated Encyclopedia
- Consolidated Event/Season Missions
- Added Mission Chain feature
Rebalanced Zombie Z Season 2
Updated Battlefield Supply
Fixed various bugs

15 July 2021

Resold Epic Decoder
Adopted Dual Dark Spirit and Astra
Resold Dual Beretta Gunslinger, Trinity Grenade, X-TRACKER, Infinity Laser Fist and Eternity Laser Fist
Held Dark Shard event
Held Bonus Disassembly event

8 July 2021

Improved Magnum Shooter perfomance
Added additional information about Purchase Request system in Mileage Auction
Fixed various bugs

6 July 2021

Adjusted some weapon levels in Zombie Z

1 July 2021

Updated Zombie Z Season 2
Held Mileage Auction
- Added Price Request System
- Added Starlight Rolling Shooter
Updated Settlement Support Weapon Box
Adopted Magnum Shooter
Recruited Anemone and Mirage (Character)
Updated Battlefield Supply

17 June 2021

Added +5 Weapon Enhancement for Air Burster, Battle PP-19 Bizon and Cyclone
Resold Boss David Black, Special Agent Criss and their costumes
Updated Transcendent Life Weapon Box and Zombie Z Starter Package
Held Special Summer Reward Giveaway
- Main Rewards: 500 Mileage, Unique Decoder, and Transcendence Decoder (1 per day)
- Special Rewards: Hunter Killer X-12, Gun Boost lvl 5 and Gun Boost lvl 6

3 June 2021

Released [Medieval Fortress] Studio Zombie map
Updated Studio and Hide and Seek device blocks
Held Studio Medieval Theme Contest
Adjusted some weapon levels in Zombie Z
Play Studio Creation mode for 30 minutes to get all Studio Theme Packs for free
Adopted M2 Devastator
Held CSO Event Ticket and Transcendent Chest events
Updated Battlefield Supply
Fixed various bugs

20 May 2021

Rereleased Dust CSO Land
Opened +5 Weapon Enhancement for Flame Jackhammer, Rail Buster, Tornado and Hunter Killer X-15
Added Flame Jackhammer, Rail Buster and Tornado to Unique Decoder
Removed Star Chaser AR, Bouncer and Stun Rifle from Unique Decoder
Updated Event Decoder content
Held CSO Land Play event
Resold Lightning Fury
Adopted Blue Storm
Open 300 Transcendence Decoder and/or 50 Premium Transcendence Decoder to obtain one of the weapons permanently

6 May 2021

Held 2021 Season 9: Fantasy World
- Reorganized some features
Held League Season 5
Updated zombie content
- Buffed zombies in rooms with zombie restrictions
- Zombie restriction quota was increased to 4
- Buffed further zombies for Normal Zombie Only restriction
- Updated Karma
- Balanced zombie meta
- Adjusted weapon levels in Zombie Z
Improved Inventory system
Updated Battlefield Supply
Fixed various bugs

22 April 2021

Added THANATOS Series to Weapon Enhancement +5
Adopted Blaze Nova
Resold Dread Nova and Epic Decoder
Held Mileage Auction
- Added Shining Heart Rod
Expanded inventory limit
Fixed various bugs

8 April 2021

Reorganized Daily Missions
Introduced Black Market
Second additional improvement for Zombie Scenario
Added Abyss difficulty for Zombie Scenario
Updated Zombie mode
Recruited Kyrix the Brave and High Elf Natasha
Updated Battlefield Supply
Fixed various bugs

25 March 2021

Replaced Blood Dripper with Thunder Ghost Walker in Transcendence Decoder
Adopted Satellite Mine
Held Seed event
Held Zombie Hero Random Rule event
Recovered an add-on item that was used irrespective of the intent due to a system error
Modified the maximum enhancement value of M95 Christmas damage from 1 to 2.
Modified the maximum enhancement value of the VICTORY series weapon enhancement items (Damage, Accuracy, Recoil, Weight, Continuous fire, and Number of rounds) to 5.

11 March 2021

Held Zombie Scenario League Season 4 Event
Held CS Online Tutorial Video Contest
Additional improvement on Zombie Scenario
Brick Piece S1451, Hunter Killer X-7, Hunter Killer X-45 and Rail Cannon can now undergo +5 Weapon Enhancement
Reworked some weapon level in Zombie Z
Held Random Weapon Zombie Hero event
Added [Security System] and [Happy New Year] medals
Updated Battlefield Supply
Added Weapon Enhancement EXP Coupon
Fixed various bugs

25 February 2021

Added Inferno difficulty to Memories
Held Valentine and Candy events
Resold Private Erica and Drill Instructor Gerard

11 February 2021

Held Mileage Auction
- Added Thunder Ghost Walker and Dual Sword Hellfire

4 February 2021

Held Letter Collecting Event
Resold Epic Decoder
Added Divine Blaster and Thunder Force
Resold Dual Beretta Gunslinger, Trinity Grenade, X-TRACKER, Infinity Laser Fist and Eternity Laser Fist in Epic Decoder
Held Divine Fragment event
Released Rex Labs
Reworked Zombie Scenario
Updated Zombie content
Renewed Hero and Sidekick weapons
Expanded Inventory by 100
Updated prizes for new/returning players
Compensated old Zombie Scenario items
Held Stingray Kite event
Held Bonus Disassembly event
Updated Battlefield Supply
Fixed various bugs

14 January 2021

Held 2021 Season 8 Event
Held Zombie League Season 3 Event
Updated Zombie modes with new contents
- Zombie-only boosting items
- Death information window and Revenge bonus system
- Zombie-only new mutation
- Zombie Z Improvements
Held Transcendent Chest
Updated Battlefield Supply
Added Zombie Z Starter Package

7 January 2021

Held Mileage Auction

2020

31 December 2020

Held New Year event
Gave away Decoders and Mileage

23 December 2020

Released Italy (Xmas)
Added Inferno difficulty to Decoy
Held Christmas Event 2020
Improved and held Mileage Auction
Resold Trinity Grenade and Thunder Ghost Walker
Thunder Ghost Walker is now available permanently from Transcendence Decoder
Resold Miracle Prism Sword and Dual Sword Hellfire
Dual Sword Hellfire is now available permanently from Unique Decoder

10 December 2020

Unleashed Draugr
Rebalanced Zombie 5: Rise and Zombie Z
Added Inferno difficulty on All-Out
Improved medal section
Held 2020 Clearance event
Recruited Leader Soi and Super Soldier Jennifer
Added Xmas Floating Damage
Updated New/Returning User prizes
Updated Battlefield Supply
Fixed various Scenario TX bugs
Updated the content of Transcendence Decoder
Added Event Decoder

26 November 2020

Added Inferno difficulty to Episode Choi
OICW, Brick Piece M777, Broad Divine and Hunter Killer X-90 can now undergo Weapon Enhancement up to +5
Held CSO Event Ticket
Held Doubled Season Pass Badge event
Fixed various bugs relating Scenario TX

12 November 2020

Patched Scenario TX
Held Zombie League Season 2 Event
Improved Medal section
Added Inferno difficulty to Zombie Scenario
Rebalanced Zombie Z and Zombie Rise
Updated Battlefield Supply
Adopted Demonic Scarlet Rose
Added Barrett M95 White Tiger permanently to Transcendence Decoder
Fixed various bugs

29 October 2020

Recruited Boss David Black and Special Agent Criss
Released Assault Halloween
Added Hunter Killer X-90 Mnemonic
Added Floating Damage Halloween
Added CSO Event Ticket

15 October 2020

Reorganized Zombie Scenario Difficulty
Released Forest Keeper
- Gave away Dual Sword Hellfire with [Leather] paint for completing the goal
Resold Gungnir with [Sigma] paint
Resold Dual Beretta Gunslinger, X-TRACKER, Trinity Grenade, Barrett M95 White Tiger, Infinity Laser Fist, M3 Black Dragon and Thunder Ghost Walker in Epic Decoder

24 September 2020

Held 2020 Season 7 Event
Reorganized League Rank system
- Held Zombie League Season 1 Event
Updated Karma system
Rebalanced Zombie Rise
- Added new medals and missions
- Added Zombie Rise to Studio (mode)
Improved Studio Create mode
- Adopted Build Marker
Adopted Negev NG-7 Ajax
Added M3 Black Dragon permanently to Transcendence Decoder
Held Find the Zombies event
Held Full Moon event
Held BALROG IS BACK event
- Added Part System support to BALROGs
- Doubled the BALROGs damage during the event
Updated Golden Zombie event
Held Mid-Autumn Festival Mileage Auction
- Added Hunter Killer X-7
- Sold Dual Beretta Gunslinger, Trinity Grenade, Holy Sword Divine Order and Magnum Launcher for Weekend Special
Fixed various bugs

17 September 2020

Held Bonus Disassembly event
- Added Eternity Laser Fist and Miracle Prism Sword to the list

3 September 2020

Adopted Miracle Prism Sword
Held Zombie Virus Overcome event
Held "Wait ! I'll go get a special weapon" event

20 August 2020

Adopted Eternity Laser Fist
Added Subscribe feature to Studio (mode)
Held Zombie Rise Random Weapon event
Added Dual Sword Phantom Slayer permanently to Transcendence Decoder
Fixed various bugs relating Studio

6 August 2020

Held Mileage Auction event
- Sold Transcendent Red Dragon Cannon Gold and Transcendent Magnum Drill Gold for Weekend Special
Resold Pink Heart Shiho, Black Rose Miho, Cyborg and Queen
Fixed various issues relating bots

23 July 2020

Patched Zombie 5: Rise
Released Junk House
Updated and held Life Weapon Box event
Held Bonus Disassembly event
Free Magnum Launcher and Holy Sword Divine Order for 15 days for New/Returned Users
Resold Shining Heart Rod and Starlight Rolling Shooter
Added more weapons to Part Weapon Selection Box
Added bot support for Gun Deathmatch
Improved bot weaponry

9 July 2020

Adopted Void Avenger and Inferno Cannon
Held Epic Fragment event
Resold Epic Decoder
Added Infernal Cannon to Epic FLEX Box
Held playtime event to obtain Epic Fragments
Held Hero event to obtain Hero and Sidekick guns for 30 days

25 June 2020

Adopted Blade Frostbreaker
Held Mileage Bingo
Added Studio Map Tag function
Improved Studio Map Recommendation
Resold Global Paint Design
Held New Global Paint Design Idea Contest
Fixed various bugs

11 June 2020

Resold Magnum Launcher and Holy Sword Divine Order
Resold Premium Transcendence Decoder
Increased SCAR OZ-C and SCAR OZ-D performance
Held Mission Supplies Event

28 May 2020

Held 2020 Season 6 Event
Reorganized Season Pass
Added Zombie Quest feature
Added Paint Switching feature
Updated Golden Zombie event
Reintroduced Weapon of the Month
Held SKULL IS BACK event
- SKULL-1, SKULL-3, SKULL-4 and SKULL-5 are given for free as part of Weapon of the Month
- All these weapons are sold directly in the shop
- The damage for these weapons and SKULL-9 is doubled
- These weapons can now undergo Weapon Enhancement (up to +4)
Updated Store
- Removed Erase Paint item
- Added Premium Moderator item
- Reorganized Mileage Duffel Bag
  - 10,000 Mileage Duffel Bag: You can freely send amounts up to 10,000 mileage.
  - 50,000 Mileage Duffel Bag: You can freely send amounts up to 50,000 mileage.
  - 100,000 Mileage Duffel Bag: You can freely send amounts up to 100,000 mileage.
  - 200,000 Mileage Duffel Bag: You can freely send amounts up to 200,000 mileage.
Held 3 days Mileage Auction
Fixed various bugs
Updated Battlefield Supply with Season Pass Coins