Based soley on what is described in the OP, vote. Which do you think is cooler? DOOM3: There is a base on Mars owned by a company called UAC who's main project is to try and figure out how to work these teleporting machines left here by an older civilization. Lately though people who used the teleportators sometimes died or just really weird things started happening to them. You are a replacement for one of those inujured. The lead scientist seems to have gone a little crazy or made a deal with the devil. In the process of maintaining it, an explosion happens and the teleporter releases all these demons into the mars facility. You try and follow the Sarges orders, but begin to doubt his judgement, also influenced by the evil doctor, who later seems to want nothing but Hell to take over. Later on, you find out that when UAC first excavated on Mars, they found these stones with writings unknown to them and some curiously advanced technology, the teleporter. Without deciphering all the stones, the scientists started to study the technology, which led to this present day disaster. The stones told of a previous civilization that had lived in Mars. They invented the teleporter, but found that when they used it they opened the gates to hell. There was a big war in, which some people lefte Mars and headed towards Earth, which was ended when some scientists created the ultimate weapon called the Soul Cube. This weapon was weilded by one man alone to close hell's gate. (I'm not sure if this is a prophecy or if it is what really happened. If they did invent the Soul Cube, then why not use it.) So you go to hell to get the soul cube, and find the demon, boss, and kick his ass and end the carnage by closing the gates. HALF-LIFE2: You are thrown by the Gman into being chased by guards. You have very little idea of what's going on. Somehow, since Black Mesa, the world was taken over by aliens who rule the world like a prison, through a pawn name Dr. Breen, who organized earth's surrender in exchange to be treated as a higher authority figure than just regular people. They want to control population growth it seems. So you try and escape to a safe place using the help of a rebel force, that thinks you're their savior until you find out that Eli Vance, one of your old colligues and major player in the rebel force, has been kidnapped by one of his colligues, Dr. Mossman for Dr. Breen. You join with Vance's daughter, Alyx, to rescue him, heading back towards the City you were trying to escape from, City 17. You attack the Dr. Breens base, the Citadel, formed of some advanced alien technology, at least it seems, and stop him from teleporting to safety by exploding his teleporter. You don't get to know what happens after the explosion other than the Gman will let you rest once more till the next job. He seems to be selling your services to some higher power.