Alien Swarm

So, there's this game on Steam called Alien Swarm. It's a real good game, it's a top view shooter game that reminds me of Alien Swarm.

Here is the trailer for it.

Here is some gameplay.

Here is a review by Games Radar
The player assumes the role of one of four classes of Marine, each with his own specialization. There’s the ‘Special Weapons’ class which enjoys the use of chain guns, flamethrowers – those kinds of things. The ‘Tech’ class solves problems that can’t be solved by bullets (yes, those problems exist even for Marines). The ‘Medic’, of course, keeps everyone stitched together. And, finally, the ‘Officer’ can buff the abilities of the rest of the team. Now, while one of each typically works best, it does not necessarily have to be so. In fact, there can be up to two of the same class (though most rounds require at least 1 specialization). Thankfully, however, responsibilities can be shared. Anyone can carry the welding torch, a single-use med pack, an additional ammo crate, or (our personal favorite) a mobile sentry gunThe game itself mainly consists of the mechanic of ‘get from the start, to the exit’ and, frankly, what happens in between is never really all that interesting. That said, however, the ride is always fast-paced as clawed xenos pop out of every darkened corner. It’s an isometric third-person view, so you’ll always see your attackers from all directions. The aiming controls are almost too precise, which means that firefights are almost never as intense as they could be. However, players will still have to work together (especially on the harder difficulties) in order to reach the exit. There are no ‘survivor closets’ in this game - once someone dies, he’s gone for the rest of the round. There is a leveling system that allows players access to newer and better gear, but you must always choose wisely. The inventory space is always very limited, and – despite what the previous sentence suggests – newer is not always better.Those who play Alien Swarm and find it a bit lacking needn’t despair though. The SDK has been released on Steam, and users are heavily encouraged to craft their own levels. Within months we should be seeing a bevy of new user content, guaranteed to keep the replayability factor good and fresh every time we care to play it. At least Alien Swarm doesn’t try to be anything other than what it is. It’s an online action shooter with plenty of things to shoot at. It might have been more atmospheric if it were in first person, but it might have been horribly broken too. So if you like blowing aliens into green little pieces, give Alien Swarm a shot. Now for those of you still on the fence, there is one more important selling point to this game: the fact that it isn’t sold at all! It’s free! That’s right, for the very reasonable price of $0, you could be blasting aliens for hours with three of your buddies. You can download it here.

Even Scrooge McDuck couldn’t resist.

I personally love this game, it's rather addictive and it's very team oriented and it's enjoyable that way.