Kinda naff
This game is a 4 player online co-op top down shooter using the Source Engine. The goal is relatively simple. Complete all the objectives and reach the end of the level and kill aliens along the way. Unfortunately, the game itself is too short, has no real sense of progression in the story as you can start from any mission you like and pick it up from there and doesn't really have a significant story. The objectives are also samey such as.... "destroy 20 alien eggs", "detonate this bomb located there" or "fix this" and every level looks almost exactly the same, like some sort of abandoned, dark, cold, snowy laboratory or open area.
The game mechanics are also an absolute pain in the arse. Some areas require you to have a certain weapon (e.g. a welder to weld open/shut a door or a flamethrower to burn alien tissue blocking your path) or a certain class (e.g. technician to hack a terminal) to progress. And this isn't even the annoying part. The annoying part is that at least one medic is an absolute necessity in this game. Why you ask? Because of a certain thing called infection.
Infections basically do a huge amount of damage over time that can kill people if not healed significantly. And healing is also a very annoying mechanic in the game. There are very few ways for even the Medic class to heal an ally, and even the most effective single target method requires a high level to even use. Its not like games like Team Fortress 2 or even World of Warcraft that have a simple, plentiful and even fun healing system in the game.
All Medics can do is either drop a limited amount of area based healing packs which heal things in its area over time (Oh wait, I forgot to tell you they cannot really be replenished easily either so you're usually stuck with that amount of healing) or a healing gun that requires a high level and has very limited ammo, unlike the Medic's healing gun from TF2 that has unlimited ammo and can overheal players.
Another annoying gameplay aspect is the top down 2D shooter aspect. Targeting enemies is often difficult without shooting teammates, and its often impossible to hit an enemy from far away or that is on a platform spitting lethal salivia at you. Whereas if it were a FPS, it would be better.
There is also a lack of aliens, you only ever meet something stupid like 3 - 4 types of aliens in total, and they all look somewhat similar to the Flood from Halo anyway.
I don't know how best to describe Alien Swarm apart from a mix of your stereotypical military squad based shooting game, Left 4 Dead, Resident Evil and maybe Grand Theft Auto's top down 2D shooter aspect. If you're into annoying gameplay mechanics, limited ammo and (especially on harder difficulties) frickin hard missions. Alien Swarm is definitely your type of game. Otherwise, this is a rather subjective review and fortunately, the game is free so you can technically try it without having to make a purchase.
