Here is the full list of all 147 Counter-Strike: Source achievements. It takes around 200 hours to unlock all of the achievements on Windows.
Collect three gifts dropped by opponents.
Get two kills standing in the same spot with a zoomed sniper rifle.
Win a match of at least 10 players where the entirety of each team is composed of a single clan.
Start a round with all players on your team wearing the same uniform (at least 5 players)
Win 100 rounds on the CS_Office map
Win 100 rounds on the CS_Italy map
Win 100 rounds on the CS_Assault map
Win 100 rounds on the CS_Militia map
Earn $50,000,000 total cash
Win 5000 rounds
Win 250 Pistol Rounds
Win 100 rounds on the CS_Havana map
Win 100 rounds on the CS_Compound map
Win 100 rounds on the DE_Aztec map
Win 100 rounds on the DE_Chateau map
Win 100 rounds on the DE_Cbble map
Win 100 rounds on the DE_Nuke map
Win 100 rounds on the DE_Inferno map
Win 100 rounds on the DE_Port map
Win 100 rounds on the DE_Tides map
Win 100 rounds on the DE_Train map
Win 100 rounds on the DE_Prodigy map
Win 100 rounds on the DE_Piranesi map
Kill a total of 20 enemy players that are dominating you
Unlock every weapon kill achievement
Kill 1,000 enemy players with the CV-47
Unlock all 10 rifle kill achievements
Kill 1,000 enemy players with the Magnum Sniper Rifle
Kill 1,000 enemy players with the Schmidt Scout
Defuse 100 bombs
Donate 100 weapons to your teammates
Kill 500 enemy players with the IDF Defender
Kill 500 enemy players with the Bullpup
Kill 1,000 enemy players with the Maverick M4A1 Carbine
Kill 10,000 enemies
Kill 500 enemy players with the Clarion 5.56
Kill 500 enemy players with the Schmidt Machine Pistol
Unlock all 5 sub-machine gun kill achievements
Kill 1,000 enemy players with the KM UMP45
Kill 1,000 enemy players with the KM Sub-Machine Gun
Kill 1,000 enemy players with the ES C90
Kill 100 zoomed-in enemy snipers
Inflict 1,000,000 total points of damage to enemy players
Spray 100 decals
Kill an airborne enemy while you are also airborne
Use Dual Elites to kill an enemy player that also has Dual Elites equipped
Kill 500 enemy players with the Krieg 550 Commando
Kill 500 enemy players with the D3/AU-1
Kill 500 enemy players with the Krieg 552
Win a round without your team killing any enemy players
Win 100 rounds on the DE_Dust map
Kill an enemy player while you are airborne
Kill a zoomed-in enemy sniper with a sniper rifle of your own
Kill a zoomed-in enemy sniper with a knife
Win 25 Pistol Rounds
Plant 100 bombs
Kill 500 enemy players with the Ingram Mac-10
Unlock both shotgun kill achievements
Kill 200 enemy players with the Leone YG1265 Auto Shotgun
Kill 200 enemy players with the Leone 12 Gauge Super
Kill 500 enemy players with the M249
Unlock all 6 Pistol kill achievements
Kill 200 enemy players with the Night Hawk .50c
Kill 200 enemy players with the 9x19 Sidearm
Kill 200 enemy players with the 228 Compact
Kill 200 enemy players with the KM Tactical .45
Kill the defuser with an HE grenade
Earn $2,500,000 total cash
Win 100 rounds on the DE_Dust2 map
Start a round on the same team as 4 of your friends, with all of you wearing the same outfit
Win 200 rounds
Kill 100 enemy players with enemy weapons
Take 80 points of damage from enemy grenades and still survive the round
Kill an enemy player who is on a killing spree
Survive a shot to the head because you had the good sense to wear a helmet
Kill an enemy player that is dominating you
Kill an enemy player who has just killed 10 of your teammates in a single round
Rescue 500 hostages
Rescue 100 hostages
Win a round by picking up the bomb from a fallen comrade and successfully planting it
Do at least 95% damage to an enemy who is then killed by a another player
Kill an enemy player in the same round as they kill a player on your friends list
Kill 100 enemy players with the ES Five-Seven
Kill 100 enemy players with the .40 Dual Elites
Kill 250 enemy players with headshots
Win 100 knife fights
Kill 500 enemy players with the HE grenade
Kill an enemy while at 1 health
Kill 100 enemy players with the knife
Kill an enemy player within 3 seconds of them recovering a dropped bomb
As the last living terrorist, distract a defuser long enough for the bomb to explode
Kill 500 enemies
Blind an enemy player who then kills a teammate
Get kills with 5 different guns in a round
Kill a total of 25 enemy players blinded by flashbangs
Survive damage from 5 different players within a round
Get a kill with every weapon
Successfully defuse a bomb with less than one second remaining
Kill an enemy with a grenade after you've died
Kill an enemy player while they are reloading
KIll an enemy player with a gun they dropped that round
Kill an enemy player who is leading the hostages without injuring any hostages
Rescue all hostages within 90 seconds
Shoot out 14 windows in a single round on cs_office
Rescue all hostages in a single round
Win 5 Pistol Rounds
Break 15 props in a single round
Inflict 50,000 total points of damage to enemy players
Kill an airborne enemy
Kill a CT while he is defusing the bomb
Plant a bomb within 25 seconds
Kill an enemy with an un-zoomed sniper rifle
Win 10 rounds without dying and not spending any cash
Defuse a bomb with a kit when it would have failed without one
Win a round by defusing a bomb
Stop defusing to kill a terrorist and then successfully finish defusing the bomb
Win a round while making no footstep noise and killing at least one enemy
Earn $125,000 total cash
Be the last player alive in a round (with at least 5 players on your team)
Do 5,000 damage with nightvision active
Kill an enemy player who has been reduced to less than 5% health by other players
Kill an enemy player with a knife during the pistol round
Win 10 rounds
Get a total of 100 kills on enemy players you are dominating
Kill an enemy player 4 additional times while you are dominating them
Win a knife fight
Get 10 kills on enemy players you are already dominating during a single match
Win a round in less than 30 seconds (against at least 5 enemy players)
Kill an opponent you are already dominating
Dominate a total of 10 enemy players
Dominate three enemy players simultaneously
Dominate an enemy player
Win a round by planting a bomb
Kill 5 players in a C4 blast
Kill an enemy with the last bullet in your magazine (excluding sniper rifles)
Kill 5 enemy players with headshots in a single round
Kill two enemy players with a single bullet
Kill two enemy players while you are blinded from a flashbang
Inflict 2,500 total points of damage to enemy players
Kill the entire enemy team (with at least 5 players) in a single round
Kill the entire opposing team without any members of your team dying
Kill the entire opposing team without any members of your team taking any damage
Kill 25 enemies
Kill 5 enemy players within 15 seconds
Kill 3 enemy players with a single HE grenade
Kill 10 enemy players in a single round
Kill an enemy player while you are blinded from a flashbang