I just finished Fallout 3, and I’m starting a second playthrough in order to get some achievements I couldn’t get the first time. If you want to get them all in one playthrough, here are a few tips:
- Disarm the megaton bomb, so that you have a house right away to store stuff in
- Look up the list of custom weapons, and as you find components, store enough of them in your house to make all the weapons. Don’t make any of the weapons yet, as it can be hard to keep track of which you make and which you find. Wait until you have the all the components and all the schematics.
- Look up the list of bobbleheads, and make sure you get them all as you go. Note that two of them are irretrievable after a certain point in the game, so it’s best to get them ASAP: medicine and energy weapons.
- Keep your karma neutral. Each time you reach one of the level milestones that gets you an achievement, save before you get the level, then level up. Then load the save, get a positive karma, and level up again. Do the same with negative karma. This will get you all three achievements, one for each karma level. Keeping a neutral karma shouldn’t be too difficult: the butler in your megaton house will give you purified water, which you can give to the beggar outside to gain karma. And you can always steal things to lose karma.