Alien Swarm

First up, Alien Swarm. This game is downloadable for free off Steam. In it, you team up with up to three other people, and you play as a squad of marines, who have to kill aliens, complete objectives and not die. The only way to loose a mission is to have the whole squad die (getting hit by a nuke after it's countdown counts as dying). You play top-down, like in Diablo, except you use the keys to move and the mouse to aim and shoot. Generally it's bad to shoot teammates, but in all the missions, you need to have the whole squad in the exit zone, and you can't do that if someone is AFK. So you have to kill him. Which uses up ammo as well, since close combat attacks don't affect teammates. And for some reason the kick button isn't working properly. This is definitely a great game. For first-timers, I'd recommend playing as Wolfe, and taking an Autogun, and heavy armor. Wolfe and Wildcat are both easy to play as, since they have no use in the game except to have an Autogun or Minigun, and kill swarms of aliens with it. Also, when playing, try not to reload, since you loose your last clip when you do. My favorite characters for each class are:

• Officer: Jaeger, with vindicator and incendiary mines. Once when I used them, we were on one side of the firewall, and the aliens kept charging into the wall and dying.
• Special weapons: Wolfe, with minigun, sentry and heavy armor. This loadout is really good in defense, since spinning the minigun (like TF2) slows you down, and the sentry is stationary.
• Medic: Faith, With Tesla gun, Medi-gun, and freeze grenades. Faith isn't as good at combat a Bastille (the other medic), but is a better healer and infestation curer, the second skill is vital in the missions including and after Syn-Tek residential (on normal difficulty). The tesla gun stuns enemies, so you can run away or melee-kill them, and the medi gun is more efficient then the heal beacon.
• Tech: Crash, with PDWs, shotgun and hand welder. The PDWs are basically dual SMGs, while the shotgun is effective against the enemies if they close on you. The hand welder lets you seal doors, which delays the swarm for ages, while they break it down.

This game seems alot like Space Hulk (space marines, minigun trooper, officers, swarms of aliens)