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