Insurgency: Sandstorm is a team-based, tactical FPS based on lethal close quarters combat and objective-oriented multiplayer gameplay. Sequel to the indie breakout FPS Insurgency, Sandstorm is reborn, improved, expanded, and bigger in every way. Experience the intensity of modern combat where skill is rewarded, and teamwork wins the fight. Prepare for a hardcore depiction of combat with deadly ballistics, light attack vehicles, destructive artillery, and HDR audio putting the fear back into the genre.
An intense atmosphere putting the terror into modern combat
Move with speed and caution as you push through the war-torn environments of a fictional contemporary conflict in the Middle East. Death comes fast, ammunition must be carefully managed, and the environment must be tactically navigated at every step toward victory.
Insurgency: refined and expanded
For the first time in an Insurgency game, customize your character to show your veterancy with diverse sets of clothing, uniforms, accessories, and character voices. Coordinate fire support with your team, engage enemies with vehicle mounted machine guns, and go head to head in small scale high speed competitive matches. Wield new weapons and new upgrades to outmaneuver, outflank, and outsmart the enemy.
War at its realest
Continuing Insurgency’s acclaim as the most atmospheric shooter, Sandstorm is built on Unreal 4 to bring its gritty close-quarters combat into a whole new era of realism. Skill is rewarded, and survival is paramount. Feel every bullet, and fear every impact.
Key Features

Sequel to the indie breakout FPS Insurgency, now with 5 million units sold. Sandstorm is reborn, improved, expanded, and bigger in every way.
Character and weapon customisation to show your battle-hardiness.
Unprecedented audio design with positional voice-chat for realistic teamwork, and heart pounding ambient audio to bring you into the battlefield.
Peek around corners, tactically breach doorways, use smoke to cover your team’s advance, and call in air support.
Battle across expansive maps in up to 16-versus-16 player game modes, or 8 player co-operative against AI, now with machine gun mounted drivable vehicles.
Competitive multiplayer features including matchmaking, broadcasting UI, and replays.

Mature Content Description

The developers describe the content like this:

This Game may contain content not appropriate for all ages, or may not be appropriate for viewing at work: Frequent Violence or Gore, General Mature Content
System Requirements

Minimum:
Requires a 64-bit processor and operating system
OS: Windows 7/8/10 (64 bits)
Processor: Intel Core i5-4440 (3.10GHz)/AMD FX-6300 (3.50GHz)
Memory: 8 GB RAM
Graphics: NVIDIA GeForce GTX 760/AMD Radeon HD 7970
DirectX: Version 11
Storage: 40 GB available space

Recommended:
Requires a 64-bit processor and operating system
OS: Windows 7/8/10 (64 bits)
Processor: Intel Core i7-8700 (3.20GHz)/AMD Ryzen 7 2700 (3.20GHz)
Memory: 16 GB RAM
Graphics: NVIDIA GeForce GTX 980/AMD Radeon R9 390X
DirectX: Version 11
Storage: 40 GB available space
Additional Notes: SSD is recommended.

https://store.steampowered.com/app/581320/Insurgency_Sandstorm/