Here is the full list of all 40 Sniper Ghost Warrior Contracts achievements. It takes around 25-30 hours to unlock all of the achievements on Windows.
Buy 57 skills
Kill enemy from each sniper rifle
Unlock 10 Sniper Rifles
Unlock 14 Gadgets
Unlock 7 Sidearms
Complete 9 of the Bounties
Complete SIBIRSKAYA-7 JUNCTION Region
Complete SIBIRSKAYA-7 JUNCTION Region on the highest difficulty
Complete 24 Challenges
Complete 24 Contracts
Kill 3 Enemies with 1 bullet
Unlock 5 Regions
Complete ARAKCHEYEV FORTRESS Region on the highest difficulty
Complete ARAKCHEYEV FORTRESS Region
Eliminate Main Target when in the vechicle with the Mine
Buy 28 skills
Complete BEKETOV VALLEY Region on the highest difficulty
Complete BEKETOV VALLEY Region
Complete 13 Contracts
Complete 13 of Challenges
Complete 5 of the Bounties
Eliminate Main Target with Remote Sniper Turret
Find 14 collectibles
Exfiltrate in under 1 minute after killing Igor Sekhov
Eliminate Main Target with The Chain kill
Eliminate Main Target with Death from above
Complete KOLCHAK HARBOR Region on the highest difficulty
Complete KOLCHAK HARBOR Region
Kill enemy from zip line
Kill 80 enemies in single mission
Kill an Enemy from a 500 meters distance.
Find 7 of collectibles
Buy your first skill
Complete ALTAI MOUNTAINS Region on the highest difficulty
Complete ALTAI MOUNTAINS Region
Interrogate an Officer
Complete first Challenge
Complete first Bounty
Find the first collectible
Complete first Contract