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The Those! achievement for Fallout 3 is worth 20 G

Go to the superduper mart and wait around for a few hours. A little boy will come to you and ask you to find his dad. Head to the town Grayditch (or something like that) and enter the fathers house. When inside loot the body and enter the shack next door and pick up the hologram. GO talk to the kid again he will be down the street near the diner now. Tell the kid you will help him and then you will need to enter the marigold metro tunnels. Deeper inside the tunnels you will meet a scientist who will give you an optional quest you can do. Kill the Ant Queen's guardians without hurting the ant queen. I deeply recommend you do this cause you get a nice perk when you finish the quest. When you go in and kill the guardians (which isn't too hard cause none of them are that close to the queen) talk to the scientist again. You will be able to choose between 2 perks Ant Sight (PER+1 and 25% fire resistance) or Ant Might (STR+1 and 25% Fire Resistance.) After this go back to the kid (he may be in his house now) and talk with him. Find him a place to live (he mentions his aunt Vera who lives in rivet city.) Go there and talk to her (she is usually in the hotel since she runs the place). Return to the kid one last time and the quest is over.