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