http://store.steampowered.com/agecheck/app/273350/

A little bit like L4D2 you have one monster and 4 hunters, it has a load of bad reviews but most of that is about the price of the game and DLCs which are all free with this version.

About This Game
Evolve is the winner of over 60 awards, and now you can play it free with Evolve Stage 2!

In a savage world of man vs nature, are you the hunter or the hunted?

Turtle Rock delivers Evolve Stage 2, the next-generation free multiplayer shooter that pits four hunters against a single, player-controlled monster.

Prove you’re the apex predator in unique 4v1 matches, progress your account and characters, and dominate the far-off world of Shear.
All content is available in-game and can be unlocked through play, for free. No buy in or box required. Evolve Stage 2 is ready for everyone.

Key Features and New Features:

Stage 2:
We’ve made improvements across-the-board including improved matchmaking, enhancements to all characters, visual improvements to maps, optimized performance, and improved player experiences. It’s a free game, but it’s also a much better game.

4v1:
Grab three friends and hunt a monster or stalk lowly humans as an ever-evolving beast. Whichever side you choose, you have access to powerful weapons and abilities that deliver balanced, competitive gameplay.
Hunt Together or Die Alone:
Choose a hunter that fits your play style. Whether you play as the Trapper, Support, Assault, or Medic, every role is vital and teamwork is key in surviving an encounter with the monster.

Beast of Prey:
As the monster – the lone predator – you are the boss battle. Use savage abilities and an animalistic sense to wreak havoc, kill the humans, and prove you are the dominant species.

Savage Planet:
Neither flora nor fauna are friendly on planet Shear. Fall victim to natural hazards or use them strategically against your prey.

Character Customization:
Level up to unlock new upgrades, skins and perks for your favorite class: hunter or monster. Earn your infamy on the leaderboards and become the apex predator

MINIMUM:
OS: Windows 7 64-bit
Processor: Core 2 Duo E6600 / Athlon 64 X2 6400
Memory: 4 GB RAM
Graphics: NVIDIA GeForce GTX 560 / ATI Radeon HD 5770
DirectX: Version 11
Storage: 50 GB available space
Sound Card: DirectX Compliant Sound card

RECOMMENDED:
OS: Windows 7 64-bit
Processor: Core i7-920 / A8-3870K
Memory: 6 GB RAM
Graphics: NVIDIA GeForce GTX 670 / ATI Radeon R9 280
DirectX: Version 11
Storage: 50 GB available space
Sound Card: DirectX Compliant Sound card