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