This is a recounting of my brother's descent into madness while playing Interplay's classic, Fallout 2.
When my brother started playing Fallout 2, I knew right away that he'd be an asshole. I try not to hold it against him, it's just what he does. Any time a game presents the player with an opportunity to be a bastard, he seizes it with both hands.
After the village elder told him of the village's troubles and sent him to the Temple of Trials to determine whether he was the chosen one, his first instinct was to beat on the guy guarding the entrance. So far, so normal. Anyway, after struggling to get through (I had to explain how to blow down a door with an explosive) he made it out, talked to the elder, and was off into the wasteland to find the Garden of Eden Creation Kit and solve the village's problems. Well, not really. Over the course of the play-through he spent about as much time searching for the GECK as you spend looking good. Er, sorry, that was uncalled for. My point is, he didn't look too hard.
Anyway, he spent a little time in Klamath before leaving to find a trader named Vic, who may have had information on the location of Vault 13 and, by extension, a GECK. I informed him Vic could be found in "the den." After arriving in the den and killing a couple of the local store owners, he found Vic, who had been captured by slavers. After working up the money to free him, he asked Vic about the location of the vault. Unfortunately, Vic didn't seem to know much, and was only able to give him the location of Vault City. When My brother asked Vic to join him and he refused (due to my brother's evil karma) he killed the poor trader with repeated stabs to the groin. Then he promptly joined the slavers.
He wasted some time doing slave runs before I managed to convince him that he should probably start thinking about doing the main quest, so off he headed to Vault City. This was where things started getting bad (or rather, worse than normal.) After attempting to talk the customs guy into letting him into the city, he said something he shouldn't have and the man called the guards. After a shootout he barely survived, Nude Politician rested until he was healed and began fighting his way out of the city. And the more he killed, the more he seemed to enjoy it. About one hour and five dead people later, he made his escape.
Now things got worse. Having lost his only lead he headed back to the den to get more slaver work, only to find that there was none. Apparently they'd been overly-zealous in their work and had either captured everyone or driven the remainder from the area. He left, unsure of where to go. Eventually he stumbled upon the Gecko, a small town inhabited by ghouls.
By this time the harsh desert waste had taken it's toll on what remained of his sanity, and he simply began murdering everyone. Before long, Gecko was reduced to a ghost town. As he left to find something else to unleash his rage upon, he was greeted with a vision of his village's shaman, urging him to find the GECK before it was too late.
He had, by now, slipped entirely into madness, and rather than heed the shaman's warning he sought to strike at it's source. Returning to his home, he lay waste to it, killing all in his sight, until he came upon in the home of the shaman. In two shots of a shotgun, the old man was killed, his lifeless body falling limply to the ground. As he left the town, he saw yet another vision, his shaman telling him that the town had died. And then, the game ended.
For whatever reason he was surprised.