Primal Fears (itch)

Due to a chemical known as pharGONe, the world has been turned upside down. Battle your way through multiple levels, earning upgrades, competing against your friends and more, and find the truth about what has happened to the world.
Use a variety of weapons to stop the mutated population, and save yourself from being another victim.
Not sure exactly what you are facing, Primal Fears harkens to the depths of the human psyche as you fight monstrous foes alone or with friends. Nothing is more scary than the unknown and it is your goal to reveal the truth...

Quotes:

"It is the kind of horror that is supposed to make you nervous for what is around the corner..."

8.5/10 - examiner.com
"Primal Fears does a great job with an atmosphere of apocalypse"

8/10 - http://leviathyn.com/games/news/2013/01/20/primal-fears/

• Co-op game play with you and your friends up to four players.
• A plethora of weapons including primary, secondary and other items of use like RC-cars, turrets, drones...
• Buy and upgrade over 15 weapons to make each play through of a level unique.
• Play the story missions or arenas that are both re-playable to challenge your skill.
• A variety of enemy types, ranging from small to hulking.
• Steam leaderboards, achievements, and cloud saving enabled.