Two teams, Counter-Terrorist & Terrorist are pit against each other on a series of levels or maps with a variety of game-modes. There have been many types but the ones that remain are CS (Hostage Rescue) DE (Bomb-Defusion) and AS (Assassination). Below is the full lengthy history of the game.

Note: Version 1.6 & CS: Source are only available through Valve’s Steam technology, full change logs can be found via that system.

Version 1.5
[6.12.02]

Changes/Additions:
» New map de_piranesi.

Bug Fixes:
» Fixed mp_hostagepenalty not working.
» Fixed problem with server locking when the bomb is planted and a new player joins the server.
» Restored “mp_fadetoblack” server variable.

Version 1.4
[4.24.02]

Changes/Additions:
» Added Anti-Cheat protection
» User Interface redone for HLTV
» Dedicated servers (Win32 + Linux) now default to 32MB heapsize.
» Improved dedicated server FPS (sys_ticrate) accuracy in Windows NT/2K/XP and Linux.
» New map cs_havana
» New map de_chateau
» Updated version of map de_train
» Enhanced in-game spectator mode to include HLTV features
» Added new first-person mode to spectator modes
» Speaking players flash in team members’ radars
» Dead bodies remain on the ground for the entire round
» Dropped bomb blinks red in Terrorist team’s radar
» Changed so only Terrorists are notified when the bomb is dropped or picked up
» Changed so players must stand still when planting the bomb (including no jumping)
» Changed so players can’t move or shoot while defusing the bomb
» Adjusted pistol accuracy while jumping (all pistols)
» Adjusted player jumping values to minimize bunny hopping
» Changed so the VIP can’t drop any weapons
» If player dies, view zooms away from falling body while changing the angle to show the killer
» Changed color of the words ‘BOMB’ and ‘VIP’ in the scoreboard to make them more visible
» Changed so name changes for dead players are stored and processed when the players respawn back into the world
» Changed the way “kevlar” and “kevlar/helmet” work using the buy menus…made them work together
» Added a sound when “kevlar” and “kevlar/helmet” are purchased
» Removed players hearing enemy radio calls
» Added code to force “sv_clienttrace 1″ on the server
» Changed so when someone mutes a player (in the scoreboard), they will no longer see that player’s in-game text messages either
» Added cheering to HLTV.
» Steam beta clients and non-Steam clients can play together on the same server now
» Voice communication uses DirectSound by default now
» Added player ID to Half-Life DM
» Added chat flood protection to HLDM.
» Added logging of fatal Sys_Error server shutdowns
» Renamed setinfo items “ah” and “vgui_menus” to “_ah” and “_vgui_menus”
» Added new setinfo item “_cl_autowepswitch” (default: 1) which controls whether or not a client switches to picked up weapons (if they’re more powerful)

New CVARS:
» “mp_kickpercent”
sets the percentage of teammates it takes to vote off a player
maximum: 1.0 minimum: 0.0 default: 0.66

» “sv_restart” acts exactly the same as “sv_restartround”

» “sv_send_logos”
when “sv_allowdownloads” is set to 1, this cvar will control whether custom logos are propagated to clients
default: 1

» “sv_send_resources” when “sv_allowdownloads” is set to 1, this cvar will control whether resources are propagated to clients
default: 1

» “cl_corpsestay”
client-side cvar to set the amount of time (in seconds) dead bodies will stay before sinking into the ground. Dead bodies are cleared at the beginning of each round.
default: 600

» “cl_righthand”
client-side cvar to toggle using the right and left hand view-models
default: 1

» “cl_minmodels”
client-side cvar so clients can play using the minimum model set: leet.mdl, gign.mdl, and vip.mdl
default: 0

Bug Fixes:
» Smoke grenade fix
» Radio command fix
» Fixed duplicate HUD weapon sprite bug
» Fixed footstep sounds to correctly play when not walking (fixes fastwalk cheats)
» Fixed uneven movement rate when moving through water
» Fixed server locking up at end of round when a lot of grenades are in play
» Fixed several ammo inconsistencies between weapons that share ammo types
» Fixed a T as CT skin bug
» Fixed bug with “kevlar/helmet” where players could buy it again at the beginning of each round even if they didn’t need it
» Fixed some view_model animation bugs
» Fixed ‘use’ key causing an instant player stop with no deceleration
» Fixed bogus \SAVE\ directory being created when you ran Half-Life.
» Fixed filter logic in the launcher.
» Fixed bug where clients couldn’t connect to server side only MODs.
» Fixed bug where you could “kill” the HLTV entity in Half-Life DM.
» Fixed AddIP command.
» Fixed crash when a func_breakable triggers a trigger_counter.
» Fixed Egon gun beam problem in Half-Life DM.
» Fixed Tau cannon prediction problem.
» Fixed fog messing Additive sprites.
» Fixed Alien Grunts not making any attack sounds.
» Fixed Egon’s beam looking yellow in sofware mode.
» Removed “friends” connectionless packet query.
» Fixed “bad address type” fatal server error (caused by clients with long names).
» Fixed “condump” so the output won’t overwrite previous files.
» Fixed “cvarlist” so the output won’t overwrite previous files.
» Fixed rcon_port and rcon_address so they can be set manually by the player to rcon a server.
» Fixed server shutdowns related to using bots.
» Fixed “vote” and “votemap” commands to work correctly
» Fixed bug where clients would try to change their name while dead and then couldn’t change it when they respawned.

Version 1.3
[9.19.01]

Changes/Additions:
» Multicast spectator added.
» Voice communication added.
» Added server chat to logging.
» Redesigned multiplayer scoreboard.
» CapsLock key is now bindable.
» Switching to Spectator is now logged.
» Changed minimum value for “mp_chattime” to 1 second
» Changed minimum value for “mp_buytime” to 0.25 (15 seconds)
» Radio commands can be heard by nearby enemies.
» Commandmenu support implemented.
New Server Variables:
mp_logdetail
Bitwise cvar to set the level of detail for logging attacks.
Bit 0 – Log Enemy Attacks
Bit 1 – Log Teammate Attacks

“mp_logdetail 0″ – Log no attacks (default)
“mp_logdetail 1″ – Log enemy attacks
“mp_logdetail 2″ – Log teammate attacks
“mp_logdetail 3″ – Log enemy AND teammate attacks

mp_startmoney
Sets the amount of starting money players may have.
maximum: 16000
minimum: 800 (default)

Bug Fixes:
» Bunny hopping removed.
» Fixed client-side shots not matching the server-side counterparts.
» Fixed banned.cfg problem with more than 1024 entries.
» Fixed screenshots overwriting each other.
» Buffer overflow exploit fixed.
» “condump”, “cmdlist”, and “cvarlist” only write out to the game directory.
» Fixed Spectator mode bug.
» Fixed hitbox issues.
» Fixed nightvision bug.
» Fixed “slot10″ not working correctly.

1.2 omitted. CS 1.0.0.2 (retail only) included Half-Life patch fixes. To allow continuity, the CS mod version stepped up to CS 1.3.

Version 1.1c
[4.6.01]

» Partial fix for incorrect hitboxes fixed when holding specific weapons.

Version 1.1
[3.10.01]

Changes/Additions:
» Added spectator mode — allow_spectators (0/1)
» Terrorist bomb backpack re-added
» Upgraded player models to 512X512 textures
» Terrorist defuse kit pack re-added
» Made jumping while shooting more inaccurate
» Took out sniper crosshair when zoomed out
» AWP leg shots now non-lethal
» Swimming animation added to models
» Status bar text uses team colors
» All CS Strings localized to titles.txt
» Added option to take “end game” screenshot
» Length of MOTD increased to 1536
» Added cs_thunder, de_rotterdam, de_inferno, & de_dust2
» Upgraded de_dust de_cbble, de_aztec, cs_siege, de_vegas, & cs_italy
» Logic used to cycle the map has been changed. The map will cycle if
one of three conditions has been met: “mp_timelimit” has been met,
“mp_winlimit” rounds have been won by one of the teams, or “mp_maxrounds”
have been played.
» Fixed many cheats
» Changed logging format to meet the standars @:

Several events have been added to the logs:
a) “Begin_Bomb_Defuse_Without_Kit”
b) “Begin_Bomb_Defuse_With_Kit”
c) “Spawned_With_The_Bomb”
d) “Dropped_The_Bomb”
e) “Got_The_Bomb”
f) “Became_VIP”
g) “Escaped_As_VIP”
h) “Round_Start”
i) “Round_End”

Bug Fixes:
» “Out of ammo” hint message fixed
» “Punished for tk” hint message fixed
» “Through floor” death animation fixed

New/Changed CVARS:
mp_playerid
Toggles what information players see in the status bar
0 everyone: players see all names listed in the status bar (with appropriate
team colors)
1 team only: players only see names for their teammates and hostages in the
status bar
2 off: players do not see any names in the status bar (hostages included)
0 is the default

mp_fadetoblack (overrides mp_forcechasecam)
0 nothing
1 player’s screen fades to black for the remainder of the round when he dies
(hud still works normally so player can chat and see the scores, etc.)
0 is the default

mp_forcechasecam
0 free to spectate anyone when player dies
1 only allowed to spectate player’s own team when player dies
2 not allowed to spectate anyone…player’s view stays where the player dies
0 is the default

mp_buytime (float)
Can now designate the desired amount of buy time for each round
min buy time is .5 minutes
no max buy time
Example: mp_buytime 1.8 // 108 seconds of buy time
1.5 min is the default (CS 1.0 buy time)

mp_roundtime (float)
Changed to support partial minutes
min round time is 1 min
max round time is 9 min
Example: mp_roundtime 1.3 // 78 seconds
5 min is the default (CS 1.0 round time)

mp_winlimit
Will cycle the map after one team reaches this many wins
0 is the default (no win limit)

mp_timelimit (float)
Fixed to support 0 (no time limit)
Example: mp_timelimit 17.2 // 17 minutes 12 seconds
0 is the default

allow_spectators
0 Do not allow spectators
1 Allow spectators

Version 1.0
[11.8.00]

» added three new weapons:
(H&K UMP .45, FN Five-Seven, & SIG SG-550)
» redone player models
» incorporated Valve’s model blending technology
» left beta stages

BETA 7.1
[9.13.00]

» fixed de_vegas crashing
» tweaked burst fire accuracy system
» slightly improved vehicle code
» included missing skies (for cs_arabstreets, de_train)
» fixed mp_timelimit bug
» added APC to cs_siege
» new server variable, “mp_maxrounds X” {X = maximum number of rounds to be played on a map, if X = 0, then maps will rotate based on mp_timelimit}
» fixed crosshairs {They now expand regardless of lag}
» fixed player heights {Player’s POV is now representative of the third person player model}
» fixed shotgun not showing up in VGUI menus in as_ maps for CTs
» included new death icon for headshots

BETA 7.0
[8.26.00]

» added dual Berettas
» added redone Knife Model (added a secondary attack mode for knife)
» fully implemented VGUI
» added new player model (Seal Team 6)
» added several new player animations
» fixed locked chasecam
» gave VIP a USP
» added cs_office, as_highrise, cs_arabstreets, de_foption & de_vegas
» fixed many bugs & exploits
» added driveable vehicle support
» added driveable vehicle test map de_jeepathon2000

New Commands:

setinfo vgui_menus X
{X = 0 or 1, 0 disables VGUI menus, 1 enables VGUI menus}
(also available through the “Play CS” > “Customize” menu)

*Note: If the buy weapon system malfunctions, disable the vgui through the “Play CS” > “Customize” menu

*Note: de_jeepathon2000 is meant as a test/prototype map only.

BETA 6.8

» Fixed server exploit.

BETA 6.7

» Fixes teleport/god mode cheats/exploits

BETA 6.6
[6.22.00]

» added new command ‘timeleft’
» fixed stalled connection bug
» new sniper crosshair
» fixes “laggy rifle firing”
» fixed many cheats
» updated cs_estate

New Commands:

timeleft
{tells you how much time is left on the map}

BETA 6.5
[6.5.00]

» Integrates Valve’s rewrite of the HL networking system
» Added Smoke Grenade
» Added “Gorilla Warface” player model
» Redone models for .45 USP, M3, SG-552, and Colt M4A1
» Added more realistic smoke f/x, and shell ejection
» Added Valve’s Chasecam modes (roam, free, and locked)
» Integrates Nighthawk’s Model Bounds Checker algorithm
» Added as_forest.bsp, de_cbble.bsp, de_aztec.bsp, as_tundra.bsp, cs_italy
» Added map voting system
» Updated maps

New Map Voting System:
———————

players type ‘listmaps’ to see the maps available to vote on, and then they type ‘votemap X’ where X is the corresponding number of the map.

Server admins who want to add new maps must also add an entry into mapcycle.txt, that allows players to vote on any new maps.

New 6.5 Commands:
—————–

fastsprites X
x = 0 : regular transparent smoke grenade sprites
x = 1 : simple transparent smoke grenade sprites
x = 2 : VERY simple transparent smoke grenade sprites

max_shells X
X = maximum number of shells at one time

max_smokepuffs X
X = max. number of smoke puffs at one time

mp_tkpunish 0/1
if set to 1, TK’ers will sit out next round

mp_hostagepenalty X
X = max. number of hostages you can kill before the server boots you out… setting this to 0 will shut off this command

mp_logmessages 0/1
used for server admins to spit ouf chat messages in their log files

mp_forcechasecam 0/1
Setting this to 1 will force chasecam to be teammate only
(useful for LAN games)

BETA 6.2a
[server side only]
» fixes camera stuck bug (when killed)
» adds “mp_tkpunish 0/1″ to toggle on the round sitting out of a TK’er
» prevents skin cheating (by using the menuselect 3 command)

BETA 6.1
[3.24.00]
[server side only]

» off center shooting fixed
» greatly improved nightvision
» can buy nightvision using the ‘buyequip’ command
» ammo bugs fixed
» 120 round limit for the mp5 and tmp
» prisoners are notified when someone escapes
» draw games eliminated, now scenario specific
» new TK 1 round “time-out” penalty

commands:
———
mp_autoteambalance 0/1
toggles the auto balancing of teams

BETA 6.0
[3.10.00]

» added MAC-10 weapon
» added Steyr Aug weapon
» added new gametype: Assassination (as_x)
» added new gametype: Escape (es_x)
» added right and left handed weapons
» added new radar tracking for teammates
» re-added Night Vision Goggles
» added new Terrorist Snow player model
» added new CT French GIGN player model
» tweaked player speeds / acceleration
» added new radio commands
» redone mp5 model / animations
» added maps de_fang, es_jail, es_frantic, as_oilrig, as_riverside, cs_747
» updated previous maps

New Beta 6.0 Commands:
———————-
+showradar (default) : Turns radar on.
-showradar : Removes radar from your screen.
nightvision : Bind this key to toggle NVG when purchased.

Misc 6.0 Notes:
—————
Assassination Gameplay: One member of the CT team will serve as the VIP. The object is to get the VIP safely to the pre-defined escape points. If he dies, the CT’s lose the round. If he makes it safely, the CT’s win. VIP has a unique skin, only carries a knife, and has ample body armor. Certain weapons cannot be purchased by each team in this gameplay scenario.

Escape Gameplay: The T team starts out in a fortified location and must “escape” to one of the pre-defined escape points. The CT’s must exterminate them before they can escape. The T’s win the round once 50% of the team has successfully escaped. They can also break into the armory to steal weapons, or just get out of there. The two teams will switch roles after every 8 rounds of play.

After buying NVG, you toggle it on/off by using the “nightvision” command. Be warned that the NVG will not be effective on every hardware setup. It may or not work well for you.

To switch between right and left hand weapons, go to: multiplayer > Customize > Advanced Options There will be a checkbox for you to select the hand of your choice.

BETA 5.2
[1.10.00]

» modified chasecam (to reduce lag)
mp_chasecam 0 : ghostmode only
mp_chasecam 1 : chasecam only
mp_chasecam 2 : both modes
» fixed crashing bugs
» updated de_train.bsp, fixed crash bug
» fixed scoreboard bugs (20 players not showing up)
» Prevented players from changing name when they’re dead
» Show scoreboard at the end of the map rotation

BETA 5.1 was a test version of BETA 5.2 for servers only.

BETA 5.0
[12.23.99]

» Added Benelli XM 1014 fully automatic shotgun
» New Hostage model and two new skins.
» SAS model added as a selectable CT
» Added maps cs_backalley and de_train
» Updated maps cs_station, de_nuke, de_dust, and de_prodigy
» New icons for HUD (money, weapons, armor, timer, C4, defuse Kit, scoreboard)
» Added buy zones, reload zones, hostage, and bomb target zones to HUD.

Gameplay Changes:
» C4 is now an equipment item in slot 5 (to plant, select then hold down fire)
» C4 can only be planted in bomb delivery zone
» To defuse a bomb Counter Terrorists must target C4, press and hold the USE key
» CTs can defuse C4 without a defuse kit in 10 seconds
» CTs can defuse C4 with a defuse kit in 5 seconds
» A progress meter is added showing CTs their progress defusing a bomb
» A progress meter is added showing Ts their progress planting a bomb (this takes 3 seconds)
» Defuse kit now an item which can be purchased – Nobody starts with a defuse kit
» Defusing bomb wins round for Counter Terrorists
» C4 can be dropped for other teammates
» Hostages are automatically rescued at hostage rescue zones
» Counter Terrorist and Terrorist teams are now labeled
» Individual frags can be toggled on or off
» Ghosts can be made visible to other ghosts (client defined)
» Pre-Round grace timer standard setting 6 seconds (server defined)
» Three observer modes: classic ghost, locked chasecam and freelook chasecam ( press jump to toggle)
» Auto-find teammate in observer mode (primary fire)
» New radio messages and organization of radio keys (standard, group and report messages)
» Can hear other players reloading
» Mission briefing added to maps (can also be invoked during round)

Context Sensitive Help System:
Terse Auto-help
» Round start notification (i.e. hint to purchase items)
» Observer mode notification

Verbose Auto-help
» What to do with hostages (CTs rescue, Ts protect)
» What not to do with hostages (injuring/killing)
» How to lead hostages
» Looking at a friend for the first time
» Looking at an enemy for the first time
» What not to do with friends (injuring/killing)
» What to do with enemies (win by killing all enemies)
» Picking up C4 for the first time
» Out of ammunition for the first time
» In a bomb target zone for the first time
» In a hostage rescue zone for the first time
Auto-ID
» Friend (name and health displayed)
» Enemy (name displayed; health displayed only if observing)
» Hostage (health displayed)

BETA 4.1
[12.1.99]

» Team chat while dead works
» Icon mixup for bomb/defuser fixed
» Slightly less money given to losers
» Allow Ts to pick up C4 if it’s not planted in the proper spot (crouch)
» Default C4 timer to 35 seconds
» Toned down P228 (and 13 rounds are default)
» Prevent players from buying stuff when they’re dead by using aliases
» Accuracies tweaked

BETA 4.0
[11.5.99]

» Added Sig P228 pistol, and Steyr Scout sniper rifle
» Added new gameplay scenario involving C4 bombs
» tweaked firing system for all guns
» added High-Explosive (HE) grenades
» modified hostage rescue scenario (rescuing 50% of the hostages will result in a CT win)
» modified kick vote system (only 65% of a team is needed to kick vote someone off)
» loose guns are removed at the start of a round. (no more gun running)
» loser bonuses are increased to allow the losing team to stand a fighting chance
» altered money bonuses for rescuing hostages :
$500 for touching a hostage
$1000 for successfully rescuing a hostage
$500 team bonus
» added cs_station, de_nuke, de_dust, de_prodigy
» modified cs_ship, cs_siege, cs_docks, cs_tire, cs_facility
» automatic flashbang .wav added back
» new, closer rescue points added to cs_ship, cs_siege, cs_tire
» changed ammo system to primary and secondary

****** What’s new in BETA 4.0 ********

** New server variables :
mp_roundtime X {X is the number of minutes the round lasts. Valid values range between 3 and 9. Default is 5}
mp_c4timer X {X is the number of seconds the C4 bomb is set to blow. Valid values range between 10 and 90. Defaults is 30}
mp_limitteams 0/1 {1 will restrict the number of players per team. Default is 1}
mp_lowlag 0/1 {0 will causes more bullet sparks to be spawned, thereby creating more lag. Default is 1}
mp_friendly_grenade_damage 0/1 {1 will result in HE grenades hurting teammates. Default is 1}

** New client commands :
+showfrags {displays every player’s frag counts on the scoreboard}
-showfrags {only displays the player’s frag count on the scoreboard}
radio1 {brings up a list of radio commands}
radio2 {brings up another list of radio commands}
plant_c4 {plants the c4 bomb, if the player has one}

***** “Defusion” C4 bombing description *****
If a map has a target to be bombed, the terrorist team leader will be equipped with a C4 bomb. His goal is to plant the bomb at the defined bomb target (marked on the map by a red target decal). Once the bomb has been planted, the bomb will blow up in X seconds (where X is the server defined C4 timer variable, default at 30 seconds). The bomb will make an increasingly louder beeping sound as it nears the detonation time. After the bomb has been planted, any Counter-terrorist player equipped with a bomb defuser may defuse the bomb by crouching on top of the bomb for 5 seconds. If the bomb goes off and the target is hit, the round will end and the Terrorists will win. If the bomb has been planted and all the terrorists are eliminated, the round will not end until the bomb has either been defused (CT wins) or detonated (Terrorist wins). A bomb’s blast radius is fairly substantial and it’s wise to give yourself 10 seconds to run away from the bomb once it’s been planted.

NOTE : Only half the CT team is equipped with bomb defusers.. It is recommended that this half of the team stay near the bomb targets to listen for any beeping sounds.

Deufusion maps are denoted by de_mapname

**Note that that ammo system is changed. You now buy either Primary or Secondary ammo. Primary being all non-pistol weapons. Secondary being all sidearms (pistolas).

BETA 3.1
[9.16.99]

» Bullet penetration bug fixed
» Radio .wav’s now have lower volume
» Removed automatic .wav’s (death, flashbang)
» fixed MRAD_ENEMYSPOTTED error
» Disorientation system changed
» Added “ignoreradio” command to only ignore .wav’s

BETA 3.0
[9.14.99]

» Added a knife weapon for those last resort situations
» Added a kevlar+helmet combination
» *GREATLY* improved hostage path AI
» Added concussion grenades which shoot out shrapnel as well as a bright flash
» Added a new weapon, the Fabrique Nationale P90 submachine gun
» Added a radio system
» Modified the scoreboard
» modified the shotgun
» siege, bunker, desert updated
» added cs_tire.bsp
» added cs_militia.bsp
» added cs_hideout.bsp
» added cs_ship.bsp
» re-added cs_mansion.bsp to map rotation

BETA 2.1
[8.17.99]

» added new vesion of cs_assault (compatible w/ hlserver.exe)
» added scientist model for hlserver.exe
» added assault’s proper sky
» fixed telefragging (cs_alley will no longer telefrag)
» fixed dropweapon
» fixed those spurious ‘player joined’ messages
» changed Ak-47 price

BETA 2.0
[8.13.99]

» Three new guns added : {Sig SG-552 Commando , AK-47 , Desert Eagle}
» Added silencers to the USP .45 Tactical and the Colt M4A1
» Added a round timer which shows how much time is left in the round
» Added team scores which shows how many rounds a team has won
» Added Night Vision Goggles
» Added new entity for mappers to use (info_hostage_rescue)
» Optimized all the models for lower r_speeds!
» Ability to assign keys to all of the commands from the controls menu (courtesy of cannelbrae of Gunman project)

BETA 1.9 (later renamed to BETA 1.2)
[7.20.99]

» 5 second “molasses period” at the start of all rounds to dissuade rushing tactics
» kick option added
» Refined the prices for some of the gunS
» made the kevlar MUCH more effective (it now covers people’s arms)
» made jumping and shooting MUCH more inaccurate for all the guns
» added a $16,000 salary cap
» tweaked the bonus money awards.
» tweaked the flashbangs effectiveness

BETA 1.1
[6.27.99]

» greatly improved server stability, crashes should be eliminated
» primary servers will now work with CS
» fixed the ammo and armour reset bugs
» balanced the economic system a bit
» added new firing mode for the glock18
» enabled ‘mp_friendlyfire’ command for server admins
» fixed map rotation
» adds two new maps: cs_assault & cs_desert
» cs_siege fixes
» cs_wpndepot fixes

BETA 1.0
[6.19.99]

» weapons: usp, glock, shotgun, m4a1, mp5 navy, TMP, awp, G3/SG-1 & FN M249 PARA
» hostage rescue scenario
» custom maps: cs_siege, cs_mansion, cs_wpndepot, cs_prison