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