Some things in Alien Swarm that I would love to see in other games of this genre:
- Shared map where you can all plan your route.
- Minimal loot, minimal stats, focus is on loadouts and interesting effects (freezing, burning, electricity etc.). Going through loot is tedious when all you are doing is increasing DPS.
- That climatic end. Believe me, if you don't spoil yourself by playing on a lower difficulty, the finale is worth the wait.
- The tactical nature of the game. This is not a game where you can succeed by spraying bullets everywhere. Friendly fire on is the default and it cannot be turned off. You even lose ammo if you reload early. However, you do have a lot of tools and weapons to work with. Bar the door, and the alien has to spend time smashing through it. Lay a wall of fire and watch the hordes melt before your eyes. But all the defenses are temporary, and the aliens can and will overpower/overrun them. You and your friends have to plan properly to use your limited resources for victory. Some of the greatest moments in this game is defending a point while hordes and hordes of aliens stream in from everywhere. All the defenses and traps we laid are exhausted but we manage to pull through.
There are some cool things in this game borrowed from third person shooters, like crouching (for cover) and calculating line of sight so you don't hit obstacles/the floor/the wall/players. Definitely makes the game feel more "grounded" and adds to the tactical layer, although I honestly don't remember if I ever used crouch.
Get some friends, play on brutal (yes, from the beginning), and have fun.
Rating... I am torn. This is honestly one of my favorite top down action games. It was just a blast playing with the guys. I really want to give it a 5/5. My only complaint is that the environments and levels themselves should have been more distinct and memorable (ex. Shock Troopers). It also doesn't have everything we want here like permadeath, and the top down perspective is inferior to the third person/first person. It came out after Killing Floor (2009), which has a lot of the things that makes Alien Swarm good. And it's better due to 6 player support and because it is first person. But Killing Floor lacks a campaign. So, 4/5.