http://www.gameswin.org/gameen.php?id=516A meteor crashed outside one of your bases. A little while later, strange aliens appeared and started killing your crew. The game begins.
As I see it, there are roughly 30 different people you can play, but only a max of 12 or so at one time. The others are off fighting the alien scourge on the different bases, presumably. In the later missions, they stuff 4 people to one person tile.
The game consists of the basic theory, "Here are people with various skills. Use what they have to solve the puzzle."
The aliens adapt quickly, and weapons that saved you last round may hurt you this round. The aliens may adapt to the plasma rifle so that instead of murderizing it, the gun caused the alien to multiply.
-Jobs-
You play many different characters, from Batista the Commander, who can use his valuable skill to call reinforcements from other bases. I have used this once, because I had to. I can never find a terminal to do it again. My favorite mission with him is him getting pissed, nuking shit with a rocket launcher, dying, and the rest of the mission is spent trying to retrieve his corpse so it can be revived.
Everyone has a name, even the aliens, but I don't remember anyone else's name. The medical officers can revive anyone, anywhere. Otherwise, you have to use a medical machine to do it.
Technicians can lock and unlock things. You don't know how valuable a locked door is against aliens.
Marines kill things. Who would have thought?
Galactic Death Bots. Yes, there are robots. One of the missions involve them going rogue, and you having to fight them and the aliens.
-Useless Jobs-
Researchers research stuff. Normally in a mission, they toss one into your group just to be a dick. Researchers are useless.
Engineers fix things, but nothing ever gets broken. Ever. Only once did something break, and that was because it plummeted from space and landed in the exact spot the meteor did.
Spy bots. They float around, and aliens usually don't attack them. Useful for spying.
Mop bots. Seriously, on one mission, I get this thing. It has a mop.
Bartender. I have no idea why he's here.
Janitor. I have a mop bot! Why do I need you?
Chef. I can use him to prepare bait. Normally, I use him for bait. They always killed him, then took the bait, then took him off to their lair. I'd have to spend too long trying to retrieve his corpse.