Recs.
Updated
Killing Floor 2 is a first-person zombie shooter with a full featured co-op campaign that takes advantage of super realistic attacks through multiple contact points on the models, giving a very realistic feel to the combat.
SpecsUpdate
Pros
Pro Cool time manipulation mechanic
Whenever a player makes a long-range headshot, messy bomb kills, or any other skillful takedown of zeds (the game's zombie-like creatures) it puts every player into 'zed time." This slow downs time, turning everything black and white, except for gunfire, explosions and blood, all beautifully rendered. Not only does it make you feel powerful, but also serves as positive reinforcement, since going into "zed time" means you or your team is doing well.
Cons
Con Currently no listen server function
Setup of a private multiplayer game can be a pain currently due to the omission of Listen server functionality. Dedicated server support is available but not well documented and can be daunting/time consuming for new users or those not technically inclined.
Con Early Access / beta state
In its current build, only has 4 of the 10 promised classes, only a hand full of weapons to choose from and 6 levels to play on. While still fun and beautiful, it lacks re-playability after 10 hours of play time. Unless the desire to play is unbearable, wait for its full release later in the Fall.
Early access or a beta state also means there may be bugs, which can detract from gameplay.