So yeah, this game is essentially Left 4 Dead, without missions. If you haven't played left 4 dead then to give you a picture here, you spawn on a map with other players and kill a bunch of mutant zombie freak-type enemies. There's a trading shop at the end of every round on a map, there are 10 rounds. You get in-game currency while playing. You get more currency for how well you do in a given round so you can buy better weapons and whatnot. There's a number of different classes to choose from, such as a pyro who uses fire-based weapons, to a melee class, healing class, marksman (headshot) class. Bunch of different classes. Cool thing is they all start at level one when you're a beginner and you can level them up as you play them. As they level, you get better bonuses and bigger advantages.
Graphics are dated but due to the style they aren't that bad to be honest. This game requires teamwork, and you can choose what difficulty you want to play on. Harder difficulties are very challenging and require teamwork. There's an ungodly amount of custom-made maps by players that are absolutely brilliant that you can play on as well, I have around 250+ hours into this game and I always find maps that I haven't tried yet.
Lotta DLC for this game. brand new one just came out which gives you brand new weapons and whatnot. Also, the developers do seasonal events for this game which is absolutely fantastic. There's nothing better than playing a game you enjoy during the seasons with a seasonal based theme. The seasonal also offers new achievements and you can unlock special skins during this short time period during seasonal events as well so it's pretty cool.
Simple game, but in this case simple is best. No story or missions or anything like that. It's a great game and it's usually on sale for 5-7 dollars. It's one of those games that is simply a must have for anyone who is a fan of killing monsters and enjoys co-op team work. It's just really addictive when you get into it and try to level up the classes. It's just mindless shooting and teamwork which sounds weak but this game makes it fun with all the cash shop each round (think counter strike) and the different classes.